scholarly journals Long-wavelength optical logging for high-resolution detection of ash layers in glacier ice

2016 ◽  
Vol 63 (237) ◽  
pp. 17-21
Author(s):  
WING S. CHAN ◽  
MERLIN L. MAH ◽  
RYAN C. BAY ◽  
JOSEPH J. TALGHADER
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Ice Core ◽  
Infrared Light ◽  
Spatial Spread ◽  
Long Wavelength ◽  
New Instrument ◽  
Siple Dome ◽  
Polar Ice Sheets ◽  
Glacier Ice

ABSTRACTA new instrument for high-resolution optical logging has been built and tested in Antarctica. Its purpose is to obtain records of volcanic products and other scattering features, such as bubbles and impurities, preserved in polar ice sheets, and it achieves this by using long wavelength near-infrared light that is absorbed by the ice before many scattering events occur. Longer wavelengths ensure that the return signal is composed primarily of a single or few backscattering event(s) that limit its spatial spread. The compact optical logger features no components on its body that draw power, which minimizes its size and weight. A prototype of the logger was built and tested at Siple Dome A borehole, and the results were correlated with prior optical logging profiles and records of volcanic products from collected ice core samples.

scholarly journals Optimization and functionalization of red-shifted rhodamine dyes

2019 ◽  
Author(s):  
Jonathan B. Grimm ◽  
Ariana N. Tkachuk ◽  
Heejun Choi ◽  
Boaz Mohar ◽  
Natalie Falco ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Near Infrared ◽  
Fluorescent Dyes ◽  
Poor Performance ◽  
Biological Imaging ◽  
Infrared Light ◽  
Long Wavelength ◽  
General Chemical ◽  
Chemical Groups ◽  
Rhodamine Dyes

ABSTRACTExpanding the palette of fluorescent dyes is vital for pushing the frontier of biological imaging. Although rhodamine dyes remain the premier type of small-molecule fluorophore due to their bioavailability and brightness, variants excited with far-red or near-infrared light suffer from poor performance due to their propensity to adopt a lipophilic, nonfluorescent form. We report a general chemical modification for rhodamines that optimizes long-wavelength variants and enables facile functionalization with different chemical groups.

Deep Near-Infrared Surveys and Young Brown Dwarf Populations in Star-Forming Regions

2003 ◽  
Vol 211 ◽  
pp. 87-90
Author(s):  
M. Tamura ◽  
T. Naoi ◽  
Y. Oasa ◽  
Y. Nakajima ◽  
C. Nagashima ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Brown Dwarf ◽  
Ir Camera ◽  
Star Forming ◽  
Star Forming Regions ◽  
New Instrument ◽  
Infrared Surveys ◽  
Low Mass

We are currently conducting three kinds of IR surveys of star forming regions (SFRs) in order to seek for very low-mass young stellar populations. First is a deep JHKs-bands (simultaneous) survey with the SIRIUS camera on the IRSF 1.4m or the UH 2.2m telescopes. Second is a very deep JHKs survey with the CISCO IR camera on the Subaru 8.2m telescope. Third is a high resolution companion search around nearby YSOs with the CIAO adaptive optics coronagraph IR camera on the Subaru. In this contribution, we describe our SIRIUS camera and present preliminary results of the ongoing surveys with this new instrument.

scholarly journals Limited migration of soluble ionic species in a Siple Dome, Antarctica, ice core

1998 ◽  
Vol 27 ◽  
pp. 371-377 ◽  
Author(s):  
Karl J. Kreutz ◽  
Paul A. Mayewski ◽  
Sallie I. Whitlow ◽  
Mark S. Twickler
Keyword(s):  
High Resolution ◽  
Sulfonic Acid ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ionic Species ◽  
Sea Salt ◽  
Methane Sulfonic Acid ◽  
Simple Diffusion ◽  
Siple Dome ◽  
Annual Resolution

High-resolution (>10 samples a−1) glaciochemical analyses covering the last 110 years from a Siplc Dome, Antarctica, ire core reveal limited migration of certain soluble ionic species (methane sulfonic acid, NO3 − and Mg2+). The observed chemical migration may be due in part to seasonal alternation between less acidic winter (from high sea-salt concentrations) and more acidic summer (from high marine biogenic acid concentrations) layers, common at coastal siles such as Siplc Dome. Exact mechanisms to expla in the migration are unclear, although simple diffusion and gravitational movement are unlikely since new peaks are formed where none previously existed in each case. Initial migration of each species is both shallower and earlier at Siple Dome than at other sites in Antarctica where similar phenomena have been observed, which may be related to the relatively low accumulation rate at Siple Dome (~13.3 cm ice a−1). Migration appears to be limited to either the preceding or following seasonal layer for each species, suggesting that paleoclimatic interpretations based on dala with lower than annual resolution are not likely to be affected.

scholarly journals Measuring Snow Specific Surface Area with 1.30 and 1.55 μm Bidirectional Reflectance Factors

2018 ◽  
Author(s):  
Adam Schneider ◽  
Mark Flanner ◽  
Roger De Roo
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Infrared Light ◽  
Micro Computed Tomography ◽  
Bidirectional Reflectance ◽  
Light Emitting ◽  
New Instrument

Abstract. Snow specific surface area (SSA) is an important physical property that directly affects solar absorption of snow cover. Instrumentation to measure snow SSA is commercially available for purchase, but these instruments are costly and/or remove and destroy snow samples during data collection. To obtain rapid, repeatable, and in situ surface snow SSA measurements, we mounted infrared light emitting diodes and photodiode detectors into a 17 cm diameter black styrene dome. By flashing light emitting diodes and measuring photodiode currents, we obtain accurate 1.30 and 1.55 micron bidirectional reflectance factors (BRFs). We compare measured snow BRFs with X-ray micro computed tomography scans and Monte Carlo photon modeling to relate BRFs to snow SSA. These comparisons show an exponential relationship between snow 1.30 micron BRFs and SSA from which we calculate calibration functions to approximate snow SSA. The techniques developed here enable rapid retrieval of snow SSA by a new instrument called the Near-Infrared Emitting and Reflectance-Monitoring Dome (NERD).

One-Photon Upconversion-Like Photolysis: A New Strategy to Achieve Long-Wavelength Light-Excitable Photolysis

Synlett ◽  
2020 ◽  
Vol 31 (12) ◽  
pp. 1129-1134 ◽  
Author(s):  
Weiping Wang ◽  
Wen Lv
Keyword(s):  
Near Infrared ◽  
Energy Utilization ◽  
Utilization Efficiency ◽  
Infrared Light ◽  
Excitation Wavelength ◽  
Long Wavelength ◽  
New Strategy ◽  
The One ◽  
Biological And Medical Applications ◽  
Wavelength Light

Photolysis reactions are widely utilized to release desired molecules under the control of light irradiation in the fields of photochemistry, biology, and drug delivery. In biological and medical applications, it is highly desired to increase the excitation wavelength for activating photolysis reactions, since the long-wavelength light (red or near-infrared light) has deep tissue penetration depth and low photocytotoxicity. Here, we briefly summarize current strategies of achieving long-wavelength light-excitable photolysis. We highlight our recently developed strategy of one-photon upconversion-like photolysis. Compared with the multiphoton upconversion-based photolysis, the one-photon strategy has a simpler energy transfer process and a higher ­energy utilization efficiency, providing a new path of activating photolysis reactions with increased excitation wavelength and photolysis quantum yield.

scholarly journals Dating firn cores by vertical strain measurements

2002 ◽  
Vol 48 (162) ◽  
pp. 401-406 ◽  
Author(s):  
Robert L. Hawley ◽  
Edwin D. Waddington ◽  
David L. Morse ◽  
Nelia W. Dunbar ◽  
Gregory A. Zielinski
Keyword(s):  
Ice Core ◽  
Video Camera ◽  
Strain Rates ◽  
West Antarctica ◽  
Polar Ice ◽  
Vertical Strain ◽  
Ash Layer ◽  
Siple Dome ◽  
Polar Ice Sheets ◽  
Rate Profile

AbstractWe have developed a system for measuring a vertical strain-rate profile in the firn on polar ice sheets using a readily available video camera to detect metal bands inserted in an air-filled hole. We used this system in 1995 and 1996 at Taylor Dome, Antarctica. We use density measurements combined with our strain rates to infer vertical velocities. From our velocities we calculate a steady-state depth–age scale for the firn at Taylor Dome. The age of a visible ash layer from 79.1 m is 675 ± 25 years; this ash can be correlated with ash found at 97.2 m in a recent ice core at Siple Dome, West Antarctica.

scholarly journals Graphene Oxide Nanoparticles Having Long Wavelength Absorbing Chlorins for Highly-Enhanced Photodynamic Therapy with Reduced Dark Toxicity

2019 ◽  
Vol 20 (18) ◽  
pp. 4344 ◽  
Author(s):  
Eun Seon Kang ◽  
Tae Heon Lee ◽  
Yang Liu ◽  
Ki-Ho Han ◽  
Woo Kyoung Lee ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Graphene Oxide ◽  
Photodynamic Therapy ◽  
Delivery System ◽  
Near Infrared ◽  
Infrared Light ◽  
Long Wavelength ◽  
Sufficient Concentration ◽  
Noncovalent Bonding ◽  
Maximum Absorption Wavelength

The long wavelength absorbing photosensitizer (PS) is important in allowing deeper penetration of near-infrared light into tumor tissue for photodynamic therapy (PDT). A suitable drug delivery vehicle is important to attain a sufficient concentration of PS at the tumor site. Presently, we developed graphene oxide (GO) nanoparticles containing long wavelength absorbing PS in the form of the chlorin derivative purpurin-18-N-ethylamine (maximum absorption wavelength [λmax] 707 nm). The GO–PS complexes comprised a delivery system in which PS was loaded by covalent and noncovalent bonding on the GO nanosheet. The two GO–PS complexes were fully characterized and compared concerning their synthesis, stability, cell viability, and dark toxicity. The GO–PS complexes produced significantly-enhanced PDT activity based on excellent drug delivery effect of GO compared with PS alone. In addition, the noncovalent GO–PS complex displayed higher photoactivity, corresponding with the pH-induced release of noncovalently-bound PS from the GO complex in the acidic environment of the cells. Furthermore, the noncovalently bound GO‒PS complex had no dark toxicity, as their highly organized structure prevented GO toxicity. We describe an excellent GO complex-based delivery system with significantly enhanced PDT with long wavelength absorbing PS, as well as reduced dark toxicity as a promising cancer treatment.

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