Thermoluminescent Phosphors for Radiation Dosimetry

The use of thermoluminescence (TL) as a method for radiation dosimetry of ionizing radiation has been established for many decades and has found many useful applications in various fields, such as personnel and environmental monitoring, retrospective dosimetry, medical dosimetry, space dosimetry, high-dose dosimetry. Method of preparation, studies and applications of thermoluminescence (TL) dosimetric materials are reviewed. Several high sensitivity thermoluminescent dosimeters (TLDs) are now commercially available in different physical forms. These commercial TL dosimeters comply with a set of stringent requirements stipulated by the International Electrotechnical Commission (IEC). Specific features of TL phosphors for thermal neutron, fast neutron and high-energy charged particle (HCP) dosimetry are also considered. Some of the recent developments in the field of optically stimulated luminescence (OSL) and radiophotoluminescence (RPL) are also summarized. Comparative advantages of TL, OSL and RPL dosimeters are given. Results of recent studies of TL in nanosized materials are briefly presented. Future challenges in this field will also be discussed. Contents of Paper

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Recent Advances in Aflatoxins Detection Based on Nanomaterials

Nanomaterials ◽

10.3390/nano10091626 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1626

Author(s):

Chunlei Yan ◽

Qi Wang ◽

Qingli Yang ◽

Wei Wu

Keyword(s):

Secondary Metabolites ◽

High Performance ◽

Aspergillus Parasiticus ◽

Animal Health ◽

High Sensitivity ◽

Simple Method ◽

Future Challenges ◽

Recent Developments ◽

Process Complexity

Aflatoxins are the secondary metabolites of Aspergillus flavus and Aspergillus parasiticus and are highly toxic and carcinogenic, teratogenic and mutagenic. Ingestion of crops and food contaminated by aflatoxins causes extremely serious harm to human and animal health. Therefore, there is an urgent need for a selective, sensitive and simple method for the determination of aflatoxins. Due to their high performance and multipurpose characteristics, nanomaterials have been developed and applied to the monitoring of various targets, overcoming the limitations of traditional methods, which include process complexity, time-consuming and laborious methodologies and the need for expensive instruments. At the same time, nanomaterials provide general promise for the detection of aflatoxins with high sensitivity, selectivity and simplicity. This review provides an overview of recent developments in nanomaterials employed for the detection of aflatoxins. The basic aspects of aflatoxin toxicity and the significance of aflatoxin detection are also reviewed. In addition, the development of different biosensors and nanomaterials for aflatoxin detection is introduced. The current capabilities and limitations and future challenges in aflatoxin detection and analysis are also addressed.

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Observation of surface morphology by reflection electron holography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154652 ◽

1989 ◽

Vol 47 ◽

pp. 536-537

Author(s):

N. Osakabe ◽

J. Endo ◽

T. Matsuda ◽

A. Tonomura

Keyword(s):

Phase Shift ◽

Surface Morphology ◽

High Sensitivity ◽

High Energy ◽

Path Difference ◽

Transmission Mode ◽

Electron Holography ◽

Dynamical Process ◽

High Vertical Resolution ◽

Amplification Technique

Progress in microscopy such as STM and TEM-TED has revealed surface structures in atomic dimension. REM has been used for the observation of surface dynamical process and surface morphology. Recently developed reflection electron holography, which employes REM optics to measure the phase shift of reflected electron, has been proved to be effective for the observation of surface morphology in high vertical resolution ≃ 0.01 Å.The key to the high sensitivity of the method is best shown by comparing the phase shift generation by surface topography with that in transmission mode. Difference in refractive index between vacuum and material Vo/2E≃10-4 owes the phase shift in transmission mode as shownn Fig. 1( a). While geometrical path difference is created in reflection mode( Fig. 1(b) ), which is measured interferometrically using high energy electron beam of wavelength ≃0.01 Å. Together with the phase amplification technique , the vertivcal resolution is expected to be ≤0.01 Å in an ideal case.

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Schottky diodes based on 2D materials for environmental gas monitoring: a review on emerging trends, recent developments and future perspectives

Journal of Materials Chemistry C ◽

10.1039/d0tc04840b ◽

2021 ◽

Author(s):

Minu Mathew ◽

Chandra Sekhar Rout

Keyword(s):

Gas Sensing ◽

2D Materials ◽

Schottky Diodes ◽

High Sensitivity ◽

Future Perspectives ◽

Working Temperature ◽

Emerging Trends ◽

Gas Sensing Properties ◽

Recent Developments ◽

Sensitivity And Selectivity

This review details the fundamentals, working principles and recent developments of Schottky junctions based on 2D materials to emphasize their improved gas sensing properties including low working temperature, high sensitivity, and selectivity.

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Persistent luminescence nanoparticles for cancer theranostics application

Journal of Nanobiotechnology ◽

10.1186/s12951-021-00862-z ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Nian Liu ◽

Xiao Chen ◽

Xia Sun ◽

Xiaolian Sun ◽

Junpeng Shi

Keyword(s):

Uv Light ◽

Combined Therapy ◽

Tumor Therapy ◽

High Sensitivity ◽

Persistent Luminescence ◽

Therapeutic Drugs ◽

High Penetration ◽

Recent Developments ◽

Cancer Theranostics

AbstractPersistent luminescence nanoparticles (PLNPs) are unique optical materials that emit afterglow luminescence after ceasing excitation. They exhibit unexpected advantages for in vivo optical imaging of tumors, such as autofluorescence-free, high sensitivity, high penetration depth, and multiple excitation sources (UV light, LED, NIR laser, X-ray, and radiopharmaceuticals). Besides, by incorporating other functional molecules, such as photosensitizers, photothermal agents, or therapeutic drugs, PLNPs are also widely used in persistent luminescence (PersL) imaging-guided tumor therapy. In this review, we first summarize the recent developments in the synthesis and surface functionalization of PLNPs, as well as their toxicity studies. We then discuss the in vivo PersL imaging and multimodal imaging from different excitation sources. Furthermore, we highlight PLNPs-based cancer theranostics applications, such as fluorescence-guided surgery, photothermal therapy, photodynamic therapy, drug/gene delivery and combined therapy. Finally, future prospects and challenges of PLNPs in the research of translational medicine are also discussed.

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The Growth of Semiconductor Thin Films Studied by RHEED

Australian Journal of Physics ◽

10.1071/ph900583 ◽

1990 ◽

Vol 43 (5) ◽

pp. 583

Author(s):

GL Price

Keyword(s):

Thin Films ◽

Surface Science ◽

High Vacuum ◽

High Energy ◽

Ultra High Vacuum ◽

Large Area ◽

Growth Modes ◽

Semiconductor Thin Films ◽

Wide Range ◽

Recent Developments

Recent developments in the growth of semiconductor thin films are reviewed. The emphasis is on growth by molecular beam epitaxy (MBE). Results obtained by reflection high energy electron diffraction (RHEED) are employed to describe the different kinds of growth processes and the types of materials which can be constructed. MBE is routinely capable of heterostructure growth to atomic precision with a wide range of materials including III-V, IV, II-VI semiconductors, metals, ceramics such as high Tc materials and organics. As the growth proceeds in ultra high vacuum, MBE can take advantage of surface science techniques such as Auger, RHEED and SIMS. RHEED is the essential in-situ probe since the final crystal quality is strongly dependent on the surface reconstruction during growth. RHEED can also be used to calibrate the growth rate, monitor growth kinetics, and distinguish between various growth modes. A major new area is lattice mismatched growth where attempts are being made to construct heterostructures between materials of different lattice constants such as GaAs on Si. Also described are the new techniques of migration enhanced epitaxy and tilted superlattice growth. Finally some comments are given On the means of preparing large area, thin samples for analysis by other techniques from MBE grown films using capping, etching and liftoff.

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Towards the Hydrogen Economy—A Review of the Parameters That Influence the Efficiency of Alkaline Water Electrolyzers

Energies ◽

10.3390/en14113193 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3193

Author(s):

Ana L. Santos ◽

Maria-João Cebola ◽

Diogo M. F. Santos

Keyword(s):

Energy Content ◽

Water Electrolysis ◽

High Energy ◽

Operating Conditions ◽

Energy Sources ◽

Alkaline Water Electrolysis ◽

Alkaline Water ◽

New Energy ◽

Recent Developments ◽

Cell Components

Environmental issues make the quest for better and cleaner energy sources a priority. Worldwide, researchers and companies are continuously working on this matter, taking one of two approaches: either finding new energy sources or improving the efficiency of existing ones. Hydrogen is a well-known energy carrier due to its high energy content, but a somewhat elusive one for being a gas with low molecular weight. This review examines the current electrolysis processes for obtaining hydrogen, with an emphasis on alkaline water electrolysis. This process is far from being new, but research shows that there is still plenty of room for improvement. The efficiency of an electrolyzer mainly relates to the overpotential and resistances in the cell. This work shows that the path to better electrolyzer efficiency is through the optimization of the cell components and operating conditions. Following a brief introduction to the thermodynamics and kinetics of water electrolysis, the most recent developments on several parameters (e.g., electrocatalysts, electrolyte composition, separator, interelectrode distance) are highlighted.

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Recent Developments In Monochromatic Microprobe X-Ray Fluorescence (MMXRF)

Microscopy and Microanalysis ◽

10.1017/s1431927600022017 ◽

1998 ◽

Vol 4 (S2) ◽

pp. 378-379

Author(s):

Z. W. Chen ◽

D. B. Wittry

Keyword(s):

Materials Science ◽

High Vacuum ◽

Three Dimensional ◽

High Sensitivity ◽

X Rays ◽

Fluorescence Excitation ◽

X Ray ◽

Quantitative Microanalysis ◽

Recent Developments ◽

Fifth Order

A monochromatic x-ray microprobe based on a laboratory source has recently been developed in our laboratory and used for fluorescence excitation. This technique provides high sensitivity (ppm to ppb), nondestructive, quantitative microanalysis with minimum sample preparation and does not require a high vacuum specimen chamber. It is expected that this technique (MMXRF) will have important applications in materials science, geological sciences and biological science.Three-dimensional focusing of x-rays can be obtained by using diffraction from doubly curved crystals. In our MMXRF setup, a small x-ray source was produced by the bombardment of a selected target with a focused electron beam and a toroidal mica diffractor with Johann pointfocusing geometry was used to focus characteristic x-rays from the source. In the previous work ∼ 108 photons/s were obtained in a Cu Kα probe of 75 μm × 43 μm in the specimen plane using the fifth order reflection of the (002) planes of mica.

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