High-Qe Photodetector for Laser Confocal

1998 ◽  
Vol 4 (S2) ◽  
pp. 418-419
Author(s):  
J. Pawley ◽  
M. Blouke ◽  
J. Janesick
Keyword(s):  
Laser Power ◽  
Materials Science ◽  
Confocal Microscope ◽  
Data Rate ◽  
Research Tool ◽  
Biological Applications ◽  
Fluorescent Marker ◽  
The Past ◽  
Optical Photon ◽  
Laser Confocal Microscope

The laser confocal microscope (LCM) is now an established research tool in biology and materials science. In biological applications, it is usually employed to detect the location of fluorescent marker molecules and, under these conditions, detected signal levels from bright areas often represent <20 photons/pixel (assuming a standard 1.6 μs pixel time) while those from dark areas are likely to average <1 photon/pixel. Although this data rate limits the speed at which information can be derived from the specimen, saturation of the fluorophor, photobleaching of the dye, and phototoxicity often prevent it being increased by simply using more laser power. Over the past 10 years, the optical photon efficiency of commercial confocal instruments has improved significantly and it is now reaching the point where further improvement is becoming very expensive. The only component is which a significant improvement is still possible is the photodetector.

How SIMS microscopy can be used in medicine

1992 ◽  
Vol 50 (2) ◽  
pp. 1602-1603
Author(s):  
Philippe Fragu
Keyword(s):  
Mass Spectrometry ◽  
Biomedical Applications ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Elements ◽  
Biological Applications ◽  
The Past ◽  
Potential Source ◽  
Secondary Ion ◽  
Chemical Integrity ◽  
Scientific Endeavour

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.

The Contribution of Intermediate-Voltage, High-Resolution Electron Microscopy In Materials Science: An Appraisal

1990 ◽  
Vol 48 (1) ◽  
pp. 478-479
Author(s):  
John L. Hutchison
Keyword(s):  
High Resolution ◽  
Materials Science ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
The Past ◽  
Resolution Electron ◽  
Extreme Sensitivity ◽  
Electron Microscopes ◽  
New Generation ◽  
Small Metal Particles

Over the past five years or so the development of a new generation of high resolution electron microscopes operating routinely in the 300-400 kilovolt range has produced a dramatic increase in resolution, to around 1.6 Å for “structure resolution” and approaching 1.2 Å for information limits. With a large number of such instruments now in operation it is timely to assess their impact in the various areas of materials science where they are now being used. Are they falling short of the early expectations? Generally, the manufacturers’ claims regarding resolution are being met, but one unexpected factor which has emerged is the extreme sensitivity of these instruments to both floor-borne and acoustic vibrations. Successful measures to counteract these disturbances may require the use of special anti-vibration blocks, or even simple oil-filled dampers together with springs, with heavy curtaining around the microscope room to reduce noise levels. In assessing performance levels, optical diffraction analysis is becoming the accepted method, with rotational averaging useful for obtaining a good measure of information limits. It is worth noting here that microscope alignment becomes very critical for the highest resolution.In attempting an appraisal of the contributions of intermediate voltage HREMs to materials science we will outline a few of the areas where they are most widely used. These include semiconductors, oxides, and small metal particles, in addition to metals and minerals.

On the Symbolism of Rain in A Farewell to Arms

2018 ◽  
Keyword(s):  
Research Tool ◽  
The Past ◽  
The World ◽  
Farewell To Arms

This paper critically analyzes the symbolic use of rain in A Farewell to Arms (1929). The researcher has applied the Sapir-Whorf Hypothesis as a research tool for the analysis of the text. This hypothesis argues that the languages spoken by a person determine how one observes this world and that the peculiarities encoded in each language are all different from one another. It affirms that speakers of different languages reflect the world in pretty different ways. Hemingway’s symbolic use of rain in A Farewell to Arms (1929) is denotative, connotative, and ironical. The narrator and protagonist, Frederick Henry symbolically embodies his own perceptions about the world around him. He time and again talks about rain when something embarrassing is about to ensue like disease, injury, arrest, retreat, defeat, escape, and even death. Secondly, Hemingway has connotatively used rain as a cleansing agent for washing the past memories out of his mind. Finally, the author has ironically used rain as a symbol when Henry insists on his love with Catherine Barkley while the latter being afraid of the rain finds herself dead in it.

Various Sensing Mechanisms for the Design of Naphthalimide based Chemosensors Emerging in Recent Years

2020 ◽  
Vol 13 (4) ◽  
pp. 262-289
Author(s):  
Duraisamy Udhayakumari
Keyword(s):  
Metal Ions ◽  
Intramolecular Charge Transfer ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Intramolecular Proton Transfer ◽  
Biological Applications ◽  
Fluorescent Chemosensors ◽  
The Past ◽  
Photo Induced Electron Transfer ◽  
Displacement Approach

In the design of novel fluorescent chemosensors, investigation of new sensing mechanisms between recognition and signal reporting units is of increasing interest. In recent years, a smart chemosensor probe containing a 1,8-naphthalimide moiety could be developed as a fluorescent and colorimetric sensor for toxic anions, metal ions, biomolecules, nitroaromatics, and acids and be further applied to monitor the relevant biological applications. In this field, several problems and challenges still exist. This critical review is mainly focused on various sensing mechanisms that have emerged in the past few years, such as Photo-Induced Electron Transfer (PET), Intramolecular Charge Transfer (ICT), Fluorescence Resonance Energy Transfer (FRET), Excited-State Intramolecular Proton Transfer (ESIPT), hydrogen bonding and displacement approach. The review concludes with some current and future perspectives, including the use of the naphthalimides for sensing anions, metal ions, biomolecules, nitroaromatics and acids and their potential uses in various fields.

SOMOphilic Alkynylation Using Acetylenic Sulfones as Functional Reagents

2021 ◽  
Author(s):  
Danhua Ge ◽  
Xin Wang ◽  
Xue-Qiang Chu
Keyword(s):  
Drug Discovery ◽  
Organic Synthesis ◽  
Materials Science ◽  
Polymer Chemistry ◽  
The Past ◽  
Acetylenic Sulfones

The past decades have witnessed a boom in alkynylation mainly owing to the importance of alkynyl-containing molecules in organic synthesis, drug discovery, polymer chemistry, and materials science. Besides conventional strategies,...

scholarly journals Database thinking and deep description: designing a digital archive of the National Synchrotron Light Source

2019 ◽  
Vol 34 (Supplement_1) ◽  
pp. i46-i57
Author(s):  
Robert Crease ◽  
Elyse Graham ◽  
Jamie Folsom
Keyword(s):  
Phase Transition ◽  
Large Scale ◽  
Materials Science ◽  
Digital Tools ◽  
Digital Archive ◽  
Big Science ◽  
National Synchrotron Light Source ◽  
The Past ◽  
The Usa ◽  
Synchrotron Light

Abstract Over the past few years, research carried out at large-scale materials science facilities in the USA and elsewhere has undergone a phase transition that affected its character and culture. Research cultures at these facilities now resemble ecosystems, comprising of complex and evolving interactions between individuals, institutions, and the overall research environment. The outcome of this phase transition, which has been gradual and building since the 1980s, is known as the New (or Ecologic) Big Science [Crease, R. and Westfall, C. (2016). The new big science. Physics Today, 69: 30–6]. In this article, we describe this phase transition, review the practical challenges that it poses for historians, review some potential digital tools that might respond to these challenges, and then assess the theoretical implications posed by “database history’.

Toxicity assessment of nanoparticles in various systems and organs

2017 ◽  
Vol 6 (3) ◽  
pp. 279-289 ◽  
Author(s):  
Yuan Yang ◽  
Zhen Qin ◽  
Wei Zeng ◽  
Ting Yang ◽  
Yubin Cao ◽  
...  
Keyword(s):  
Predictive Models ◽  
Toxicity Assessment ◽  
Biological Applications ◽  
Standard Methods ◽  
Immune Systems ◽  
The Past ◽  
Injury Mechanisms ◽  
Histopathological Studies

AbstractIn the past decades, much attention has been paid to toxicity assessment of nanoparticles prior to clinical and biological applications. Whilein vitrostudies have been increasing constantly,in vivostudies of nanoparticles have not established a unified system until now. Predictive models and validated standard methods are imperative. This review summarizes the current progress in approaches assessing nanotoxicity in main systems, including the hepatic and renal, gastrointestinal, pulmonary, cardiovascular, nervous, and immune systems. Histopathological studies and specific functional examinations in each system are elucidated. Related injury mechanisms are also discussed.

Plutonium in Crystalline Ceramics and Glasses

MRS Bulletin ◽  
2001 ◽  
Vol 26 (9) ◽  
pp. 698-706 ◽  
Author(s):  
Isabelle Muller ◽  
William J. Weber
Keyword(s):  
Long Range ◽  
Nuclear Waste ◽  
Materials Science ◽  
Ceramic Matrix ◽  
Range Order ◽  
Long Range Order ◽  
Geologic Time ◽  
The Past ◽  
Geologic Time Scale ◽  
High Flexibility

The investigation of plutonium in glasses (amorphous ceramics lacking long-range order), in crystalline ceramics, and in composite materials composed of multiple crystalline or glass and crystalline phases, relieson multidisciplinary studies of physics, chemistry, and materials science. It involves the study of the plutonium atoms in materials with only short-range periodicity, as in glasses, to materials with long-range periodicity, as in crystals. The materials studied over the past 30 years include simple binary crystals, used to investigate the electronic structure of plutonium, to complex glasses and ceramics selected not only for the safety and durability that they provide for the immobilization of nuclear waste and plutonium, but also for the high flexibility they offer in composition. The lack of long-range order at the atomic level in glasses permits the inclusion of abroad range of waste elements, but it renders more difficult the interpretation of data from many commonly used experimental techniques. Regardless of the challenge, much of the research conducted in this field over the past few decades has been motivated by the use of plutonium as a surrogate for all nuclear-waste actinides or on its own in immobilization studies, in order to develop a durable glass or ceramic matrix that can resist leaching and mobilization of the plutonium on a geologic time scale.

Sign in / Sign up

Export Citation Format

Share Document