Single-nanowire spectrometers

Spectrometers with ever-smaller footprints are sought after for a wide range of applications in which minimized size and weight are paramount, including emerging in situ characterization techniques. We report on an ultracompact microspectrometer design based on a single compositionally engineered nanowire. This platform is independent of the complex optical components or cavities that tend to constrain further miniaturization of current systems. We show that incident spectra can be computationally reconstructed from the different spectral response functions and measured photocurrents along the length of the nanowire. Our devices are capable of accurate, visible-range monochromatic and broadband light reconstruction, as well as spectral imaging from centimeter-scale focal planes down to lensless, single-cell–scale in situ mapping.

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Single-cell analysis in situ in a Bacillus subtilis swarming community identifies distinct spatially separated subpopulations differentially expressing hag (flagellin), including specialized swarmers

Microbiology ◽

10.1099/mic.0.047159-0 ◽

2011 ◽

Vol 157 (9) ◽

pp. 2456-2469 ◽

Cited By ~ 20

Author(s):

Kassem Hamze ◽

Sabine Autret ◽

Krzysztof Hinc ◽

Soumaya Laalami ◽

Daria Julkowska ◽

...

Keyword(s):

Bacillus Subtilis ◽

Single Cell ◽

Single Cell Analysis ◽

Laboratory Strain ◽

Cell Types ◽

Spatiotemporal Pattern ◽

Cell Analysis ◽

Wide Range ◽

Low Humidity

The non-domesticated Bacillus subtilis strain 3610 displays, over a wide range of humidity, hyper-branched, dendritic, swarming-like migration on a minimal agar medium. At high (70 %) humidity, the laboratory strain 168 sfp + (producing surfactin) behaves very similarly, although this strain carries a frameshift mutation in swrA, which another group has shown under their conditions (which include low humidity) is essential for swarming. We reconcile these different results by demonstrating that, while swrA is essential for dendritic migration at low humidity (30–40 %), it is dispensable at high humidity. Dendritic migration (flagella- and surfactin-dependent) of strains 168 sfp + swrA and 3610 involves elongation of dendrites for several hours as a monolayer of cells in a thin fluid film. This enabled us to determine in situ the spatiotemporal pattern of expression of some key players in migration as dendrites develop, using gfp transcriptional fusions for hag (encoding flagellin), comA (regulation of surfactin synthesis) as well as eps (exopolysaccharide synthesis). Quantitative (single-cell) analysis of hag expression in situ revealed three spatially separated subpopulations or cell types: (i) networks of chains arising early in the mother colony (MC), expressing eps but not hag; (ii) largely immobile cells in dendrite stems expressing intermediate levels of hag; and (iii) a subpopulation of cells with several distinctive features, including very low comA expression but hyper-expression of hag (and flagella). These specialized cells emerge from the MC to spearhead the terminal 1 mm of dendrite tips as swirling and streaming packs, a major characteristic of swarming migration. We discuss a model for this swarming process, emphasizing the importance of population density and of the complementary roles of packs of swarmers driving dendrite extension, while non-mobile cells in the stems extend dendrites by multiplication.

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Spectrum projection with a bandgap-gradient perovskite cell for colour perception

Light Science & Applications ◽

10.1038/s41377-020-00400-w ◽

2020 ◽

Vol 9 (1) ◽

Author(s):

Mei-Na Zhang ◽

Xiaohan Wu ◽

Antoine Riaud ◽

Xiao-Lin Wang ◽

Fengxian Xie ◽

...

Keyword(s):

High Efficiency ◽

Optoelectronic Devices ◽

Photon Flux ◽

Spectral Information ◽

In Situ Characterization ◽

Colour Perception ◽

Spectral Signal ◽

Wide Range ◽

Good Agreement

Abstract Optoelectronic devices for light or spectral signal detection are desired for use in a wide range of applications, including sensing, imaging, optical communications, and in situ characterization. However, existing photodetectors indicate only light intensities, whereas multiphotosensor spectrometers require at least a chip-level assembly and can generate redundant signals for applications that do not need detailed spectral information. Inspired by human visual and psychological light perceptions, the compression of spectral information into representative intensities and colours may simplify spectrum processing at the device level. Here, we propose a concept of spectrum projection using a bandgap-gradient semiconductor cell for intensity and colour perception. Bandgap-gradient perovskites, prepared by a halide-exchanging method via dipping in a solution, are developed as the photoactive layer of the cell. The fabricated cell produces two output signals: one shows linear responses to both photon energy and flux, while the other depends on only photon flux. Thus, by combining the two signals, the single device can project the monochromatic and broadband spectra into the total photon fluxes and average photon energies (i.e., intensities and hues), which are in good agreement with those obtained from a commercial photodetector and spectrometer. Under changing illumination in real time, the prepared device can instantaneously provide intensity and hue results. In addition, the flexibility and chemical/bio-sensing of the device via colour comparison are demonstrated. Therefore, this work shows a human visual-like method of spectrum projection and colour perception based on a single device, providing a paradigm for high-efficiency spectrum-processing applications.

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Classification of Australian Waterbodies across a Wide Range of Optical Water Types

Remote Sensing ◽

10.3390/rs12183018 ◽

2020 ◽

Vol 12 (18) ◽

pp. 3018

Author(s):

Elizabeth J. Botha ◽

Janet M. Anstee ◽

Stephen Sagar ◽

Eric Lehmann ◽

Thais A. G. Medeiros

Keyword(s):

Spectral Response ◽

Optical Observations ◽

Optical Data ◽

Water Types ◽

Continental Scale ◽

Inherent Optical Properties ◽

Eastern Australia ◽

Wide Range ◽

Development Goals

Baseline determination and operational continental scale monitoring of water quality are required for reporting on marine and inland water progress to Sustainable Development Goals (SDG). This study aims to improve our knowledge of the optical complexity of Australian waters. A workflow was developed to cluster the modelled spectral response of a range of in situ bio-optical observations collected in Australian coastal and continental waters into distinct optical water types (OWTs). Following clustering and merging, most of the modelled spectra and modelled specific inherent optical properties (SIOP) sets were clustered in 11 OWTs, ranging from clear blue coastal waters to very turbid inland lakes. The resulting OWTs were used to classify Sentinel-2 MSI surface reflectance observations extracted over relatively permanent water bodies in three drainage regions in Eastern Australia. The satellite data classification demonstrated clear limnological and seasonal differences in water types within and between the drainage divisions congruent with general limnological, topographical, and climatological factors. Locations of unclassified observations can be used to inform where in situ bio-optical data acquisition may be targeted to capture a more comprehensive characterization of all Australian waters. This can contribute to global initiatives like the SDGs and increases the diversity of natural water in global databases.

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Size-dependent Photovoltaic Properties of Solar Cells Containing Si Quantum Dots/SiC Multilayers

10.21203/rs.3.rs-17255/v1 ◽

2020 ◽

Author(s):

Yunqing Cao ◽

Dong Wu ◽

Ping Zhu ◽

Zhaoyun Ge ◽

Wei Li ◽

...

Keyword(s):

Solar Cells ◽

Spectral Response ◽

Quantum Confinement Effect ◽

Solar Spectrum ◽

Visible Range ◽

Photovoltaic Properties ◽

Heterojunction Solar Cells ◽

Size Dependent ◽

Wide Range ◽

Si Nanostructures

Abstract Recently, many kinds of Si nanostructures have been extensively investigated, in which, Si quantum dot (Si QD) is one of the potential candidates for all-Si tandem solar cells. Because the optical bandgap of Si QDs can be tunable via size controlling, it can match the solar spectrum in a wide range and consequently improve the spectral response. In this work, Si QDs/SiC multilayers with controllable dot sizes were fabricated and characterized. The Raman spectra and transmission electron microscopy (TEM) observation revealed the formation of size-controllable Si QDs. The absorption measurement showed that the bandgap of Si QDs was red shifted to the long wavelength range with the dot size increasing, which agrees well with the quantum confinement effect. Moreover, heterojunction solar cells containing different sized-Si QDs/SiC multilayers were proposed and investigated. The solar cells exhibited strong size-dependent photovoltaic properties and the best cell had the power conversion efficiency (PCE) of 7.27%. Furthermore, the external quantum efficiency (EQE) measurement demonstrated the Si QDs contribution of light absorption and response in ultraviolet-visible range, which provides a promising way to realize better spectral match by applying different sized-Si QDs in the future photovoltaic devices.

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In-situ electrical-resistivity measurements in the high-voltage electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107484 ◽

1978 ◽

Vol 36 (1) ◽

pp. 68-69

Author(s):

W. E. King

Keyword(s):

Electrical Resistivity ◽

Electron Microscope ◽

High Voltage ◽

Resistivity Measurements ◽

Voltage Electron ◽

High Voltage Electron Microscope ◽

High Voltage Electron ◽

Wide Range ◽

Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

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Characterization of the glycoconjugates of boar testis and epididymis

Reproduction ◽

10.1530/reprod/120.2.325 ◽

2000 ◽

pp. 325-335 ◽

Cited By ~ 29

Author(s):

A Calvo ◽

LM Pastor ◽

S Bonet ◽

E Pinart ◽

M Ventura

Keyword(s):

Ricinus Communis ◽

Lectin Histochemistry ◽

Apical Part ◽

Seminiferous Tubules ◽

In Situ Characterization ◽

Intense Staining ◽

Terminal Galactose ◽

Boar Spermatozoa

Lectin histochemistry was used to perform in situ characterization of the glycoconjugates present in boar testis and epididymis. Thirteen horseradish peroxidase- or digoxigenin-labelled lectins were used in samples obtained from healthy fertile boars. The acrosomes of the spermatids were stained intensely by lectins with affinity for galactose and N-acetyl-galactosamine residues, these being soybean, peanut and Ricinus communis agglutinins. Sertoli cells were stained selectively by Maackia ammurensis agglutinin. The lamina propria of seminiferous tubules showed the most intense staining with fucose-binding lectins. The Golgi area and the apical part of the principal cells of the epididymis were stained intensely with many lectins and their distribution was similar in the three zones of the epididymis. On the basis of lectin affinity, both testis and epididymis appear to have N- and O-linked glycoconjugates. Spermatozoa from different epididymal regions showed different expression of terminal galactose and N-acetyl-galactosamine. Sialic acid (specifically alpha2,3 neuraminic-5 acid) was probably incorporated into spermatozoa along the extratesticular ducts. These findings indicate that the development and maturation of boar spermatozoa are accompanied by changes in glycoconjugates. As some lectins stain cellular or extracellular compartments specifically, these lectins could be useful markers in histopathological evaluation of diseases of boar testis and epididymis.

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Site specific agricultural soil management with the use of new technologies

Global NEST Journal ◽

10.30955/gnj.001203 ◽

2013 ◽

Vol 16 (1) ◽

pp. 59-67

Keyword(s):

New Technologies ◽

Digital Interface ◽

Appropriate Treatment ◽

Wide Range ◽

Soil Variation ◽

Soil Information ◽

Remote Sensing Techniques ◽

Agricultural Areas

<p>The Soil Science Institute of Thessaloniki produces new digitized Soil Maps that provide a useful electronic database for the spatial representation of the soil variation within a region, based on in situ soil sampling, laboratory analyses, GIS techniques and plant nutrition mathematical models, coupled with the local land cadastre. The novelty of these studies is that local agronomists have immediate access to a wide range of soil information by clicking on a field parcel shown in this digital interface and, therefore, can suggest an appropriate treatment (e.g. liming, manure incorporation, desalination, application of proper type and quantity of fertilizer) depending on the field conditions and cultivated crops. A specific case study is presented in the current work with regards to the construction of the digitized Soil Map of the regional unit of Kastoria. The potential of this map can easily be realized by the fact that the mapping of the physicochemical properties of the soils in this region provided delineation zones for differential fertilization management. An experiment was also conducted using remote sensing techniques for the enhancement of the fertilization advisory software database, which is a component of the digitized map, and the optimization of nitrogen management in agricultural areas.</p>

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In-Situ Dual Beam (FIBSEM) Techniques for Probe Pad Deposition and Dielectric Integrity Inspection in 0.2 μm Technology DRAM Single Cells

ISTFA 1999: Conference Proceedings from the 25th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa1999p0311 ◽

1999 ◽

Author(s):

Gunnar Zimmermann ◽

Richard Chapman

Keyword(s):

Electron Beam ◽

Single Cell ◽

Single Cells ◽

Ion Beam ◽

Gate Oxide ◽

Ion Milling ◽

Dual Beam ◽

Sem Imaging ◽

Innovative Techniques

Abstract Dual beam FIBSEM systems invite the use of innovative techniques to localize IC fails both electrically and physically. For electrical localization, we present a quick and reliable in-situ FIBSEM technique to deposit probe pads with very low parasitic leakage (Ipara < 4E-11A at 3V). The probe pads were Pt, deposited with ion beam assistance, on top of highly insulating SiOx, deposited with electron beam assistance. The buried plate (n-Band), p-well, wordline and bitline of a failing and a good 0.2 μm technology DRAM single cell were contacted. Both cells shared the same wordline for direct comparison of cell characteristics. Through this technique we electrically isolated the fail to a single cell by detecting leakage between the polysilicon wordline gate and the cell diffusion. For physical localization, we present a completely in-situ FIBSEM technique that combines ion milling, XeF2 staining and SEM imaging. With this technique, the electrically isolated fail was found to be a hole in the gate oxide at the bad cell.

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