Porphyrazines: Designer Macrocycles by Peripheral Substituent Change

2008 ◽  
Vol 61 (4) ◽  
pp. 235 ◽  
Author(s):  
Matthew J. Fuchter ◽  
Chang Zhong ◽  
Hong Zong ◽  
Brian M. Hoffman ◽  
Anthony G. M. Barrett
Keyword(s):  
Optical Properties ◽  
Surface Chemistry ◽  
Optical Sensors ◽  
Driving Force ◽  
Historical Overview ◽  
Unique Position ◽  
Naturally Occurring ◽  
New Strategies ◽  
Direct Fusion ◽  
Molecular Unit

It is rare that such a diverse array of applications can be realized from a single basic molecular unit, however, such is the power of the tetrapyrrolic macrocycle motif. Indeed, their potential in areas such as chemical dyes, optical sensors, optoelectronics, and biomedical agents is a function of their rich electronic and optical properties. While the naturally occurring porphyrins and the synthetic phthalocyanines have been extensively studied, the related tetraazaporphyrins or porphyrazines remain comparatively underdeveloped. Since porphyrazines maintain a unique position in this family: analogous derivatives are virtually inaccessible for the porphyrins, and direct fusion of heteroatomic substituents onto the porphyrazine β-positions results in a more pronounced effect compared with the substitution of an equivalent group onto the benzenoid rings of the phthalocyanine; a driving force exists to further explore the synthesis and applications of these novel macrocycles. This review will provide a historical overview of the synthetic strategies towards functionalized porphyrazines and describe new strategies towards the preparation and applications of heteroatom-appended porphyrazines, particularly in the context of their multimetallic complexes, catalysis, surface chemistry, and as biomedical agents.

Fluorescent Nanotechnology: An Evolution in Optical Sensors

2020 ◽  
Vol 17 ◽  
Author(s):  
Dilawar Hassan ◽  
Hadi Bakhsh ◽  
Asif M. Khurram ◽  
Shakeel A. Bhutto ◽  
Nida S. Jalbani ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Sensors ◽  
Light Emission ◽  
Environmental Contaminants ◽  
Fluorescent Nanoparticles ◽  
Sensing Applications ◽  
Properties Of Materials ◽  
Optical Properties Of Materials ◽  
Fluorescent Nanomaterials

Background: The optical properties of nanomaterials have evolved enormously with the introduction of nanotechnology. The property of materials to absorb and/or emit specific wavelength has turned them into one of the most favourite candidates to be effectively utilized in different sensing applications e.g organic light emission diodes (OLEDs) sensors, gas sensors, biosensors and fluorescent sensors. These materials have been reported as a sensor in the field of tissue and cell imaging, cancer detection and detection of environmental contaminants etc. Fluorescent nanomaterials are heling in rapid and timely detection of various contaminants that greatly impact the quality of life and food, that is exposed to these contaminants. Later, all the contaminants have been investigated to be most perilous entities that momentously affect the life span of the animals and humans who use those foods which have been contaminated. Objective: In this review, we will discuss about various methods and approaches to synthesize the fluorescent nanoparticles and quantum dots (QDs) and their applications in various fields. The application will include the detection of various environmental contaminants and bio-medical applications. We will discuss the possible mode of action of the nanoparticles when used as sensor for the environmental contaminants as well as the surface modification of some fluorescent nanomaterials with anti-body and enzyme for specific detection in animal kingdom. We will also describe some RAMAN based sensors as well as some optical sensing-based nanosensors. Conclusion: Nanotechnology has enabled to play with the size, shape and morphology of materials in the nanoscale. The physical, chemical and optical properties of materials change dramatically when they are reduced to nanoscale. The optical properties can become choosy in terms of emission or absorption of wavelength in the size range and can result in production of very sensitive optical sensor. The results show that the use of fluorescent nanomaterials for the sensing purposes are helping a great deal in the sensing field.

scholarly journals Structural and optical properties of amorphous Si–Ge–Te thin films prepared by combinatorial sputtering

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. Mihai ◽  
F. Sava ◽  
I. D. Simandan ◽  
A. C. Galca ◽  
I. Burducea ◽  
...  
Keyword(s):  
Optical Properties ◽  
Data Storage ◽  
Optical Sensors ◽  
Material Selection ◽  
Functional Materials ◽  
Stability Study ◽  
Optical Data Storage ◽  
Optical Data ◽  
Structural And Optical Properties ◽  
Topological Constraint

AbstractThe lack of order in amorphous chalcogenides offers them novel properties but also adds increased challenges in the discovery and design of advanced functional materials. The amorphous compositions in the Si–Ge–Te system are of interest for many applications such as optical data storage, optical sensors and Ovonic threshold switches. But an extended exploration of this system is still missing. In this study, magnetron co-sputtering is used for the combinatorial synthesis of thin film libraries, outside the glass formation domain. Compositional, structural and optical properties are investigated and discussed in the framework of topological constraint theory. The materials in the library are classified as stressed-rigid amorphous networks. The bandgap is heavily influenced by the Te content while the near-IR refractive index dependence on Ge concentration shows a minimum, which could be exploited in applications. A transition from a disordered to a more ordered amorphous network at 60 at% Te, is observed. The thermal stability study shows that the formed crystalline phases are dictated by the concentration of Ge and Te. New amorphous compositions in the Si–Ge–Te system were found and their properties explored, thus enabling an informed and rapid material selection and design for applications.

Carp chemical sensing and the potential of natural environmental attractants for control of carp: a review

2009 ◽  
Vol 6 (5) ◽  
pp. 357 ◽  
Author(s):  
Aaron Elkins ◽  
Russell Barrow ◽  
Simone Rochfort
Keyword(s):  
Pest Management ◽  
Native Fish ◽  
Major Focus ◽  
Naturally Occurring ◽  
Management Scheme ◽  
Significant Damage ◽  
Minimal Environmental Impact ◽  
Impact On Biodiversity ◽  
New Strategies ◽  
Control And Eradication

Environmental context. Carp are responsible for causing significant damage to lakes and rivers resulting in highly turbid water impacting native fish. At present there are no effective ways to manage the damage caused by carp or eradicate them, but the efficiency of carp removal from our waterways can be enhanced by the development of naturally occurring environmental attractants. As part of a broader pest management scheme the implementation of these attractants can significantly enhance the effectiveness of eradication programs and lead to the restoration of our waterways. Abstract. Cyprinus carpio, a species of carp commonly known as European or common carp, are invasive alien species in Australian inland waters and have an extensive impact on biodiversity and the aquatic environment. The control and eradication of carp is a major focus of fisheries services throughout Australia, but at present there is no wholly successful way to limit the damage caused. An integrated pest management scheme (IPM) is the most likely approach to be effective. Such a scheme could employ current tactics such as trapping in combination with new strategies including attractants or deterrents. Among proposed attractants are environmentally derived chemicals. Carp have long been observed to prefer certain habitats and environmental conditions over others, although the reasons for such a preference are not well defined. This article reviews the current scientific literature for chemical reception and attraction in carp with an emphasis on environmentally derived attractants and the potential for use of these chemical cues to enhance IPM strategies with minimal environmental impact.

A Nanoscale Adventure with Silicon: Synthesis, Surface Chemistry, and other Surprises

2015 ◽  
Vol 242 ◽  
pp. 383-390
Author(s):  
Md Hosnay Mobarok ◽  
Tapas K. Purkait ◽  
Jonathan G.C. Veinot
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Surface Chemistry ◽  
Research Group ◽  
Size Dependent ◽  
Earth Abundant ◽  
Potential Applications ◽  
Si Quantum Dots

The preparation and surface chemistry Si quantum dots (SiQDs) are currently an intense focus of research because of their size dependent optical properties and many potential applications. SiQDs offer several advantages over other quantum dots; Si is earth abundant, non-toxic and biocompatible. This account briefly highlights recent advancements made by our research group related to the synthesis, functionalization, surface dependent optical properties and applications of SiQDs.

scholarly journals Determining Bottom Reflectance and Water Optical Properties Using Unmanned Underwater Vehicles under Clear or Cloudy Skies

2006 ◽  
Vol 23 (2) ◽  
pp. 314-324 ◽  
Author(s):  
David C. English ◽  
Kendall L. Carder
Keyword(s):  
Optical Properties ◽  
Water Column ◽  
Optical Sensors ◽  
Light Field ◽  
Field Measurements ◽  
Underwater Vehicles ◽  
Unmanned Underwater Vehicles ◽  
Cloudy Weather ◽  
Sea Grass ◽  
Ocean Color Imagery

Abstract An unmanned underwater vehicle (UUV) with hyperspectral optical sensors that measure downwelling irradiance and upwelling radiance was deployed over sandy bottoms, sea grass patches, and coral reefs near Lee Stocking Island, Bahamas, during the Coastal Benthic Optical Properties (CoBOP) program of 2000. These deployments occurred during both sunny and cloudy weather. If the rate of irradiance change due to cloud cover is slight, then the inclusion of a variable cloudy-irradiance factor will allow a reasonable estimation of water column absorption. Examination of data from a deployment in May 2000 under cloudy skies shows that the combination of hyperspectral light-field measurements, knowledge of the UUV's position in the water column, and a cloudy-irradiance factor permits consistent estimations of bottom reflectivity to be made from UUV measured reflectances. The spatial distribution of reflectance estimates obtained from a UUV may be useful for validation of airborne ocean color imagery.

scholarly journals An investigation on the optical properties of regioregular Poly(3-Hexylthiophene)

2014 ◽  
Vol 17 (2) ◽  
pp. 86-92
Author(s):  
Lam Le ◽  
Tuan Anh Luu
Keyword(s):  
Optical Properties ◽  
Optical Sensors ◽  
Field Effect Transistors ◽  
Gel Permeation Chromatography ◽  
Semiconducting Polymers ◽  
Organic Field Effect Transistors ◽  
Thermal Stabilities ◽  
Smart Windows ◽  
Regioregular Poly ◽  
Ft Ir

Among semiconducting polymers, poly(3-alkylthiophene)s have attracted great attention and generated many studies over the past few years. Among them, regioregular (head-to-tail) poly(3-hexylthiophene) (P3HT) has been especially investigated due to its superior opto-electronic properties, good solubility in the most common organic solvents, chemical and thermal stabilities and also very low toxicity. These properties enable P3HT to be significantly useful in a large variety of applications such as optical sensors, smart windows, organic field effect transistors (OFETs), electrochromic devices, and solar cells. Here, we report the synthesis of poly(3-hexylthiophene) (P3HT) and investigate the optical properties of P3HT in different solvents such as chloroform, tetrahydrofuran, toluene, ethylacetate. The structures of P3HT were confirmed by nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), Fourier transform infrared (FT-IR).

scholarly journals Symmetry Breakdown in Franckeite: Spontaneous Strain, Rippling and Interlayer Moiré

2019 ◽  
Author(s):  
Riccardo Frisenda ◽  
Gabriel Sanchez-Santolino ◽  
Nikos Papadopoulos ◽  
Joanna Urban ◽  
Michal Baranowski ◽  
...  
Keyword(s):  
Optical Properties ◽  
Plane Strain ◽  
Van Der Waals ◽  
Van Der Waals Interaction ◽  
Spatial Modulation ◽  
Two Dimensional ◽  
Spontaneous Strain ◽  
Strain Profile ◽  
Symmetry Breakdown ◽  
Naturally Occurring

<p>Franckeite is a naturally occurring layered mineral with a structure composed of alternating stacks of SnS<sub>2</sub>-like and PbS-like layers. Although this superlattice is composed of a sequence of isotropic two-dimensional layers, it exhibits a spontaneous rippling that makes the material structurally anisotropic. We demonstrate that this rippling comes hand in hand with an inhomogeneous in-plane strain profile and anisotropic electrical, vibrational and optical properties. We argue that this symmetry breakdown results from a spatial modulation of the van der Waals interaction between layers due to the SnS<sub>2</sub>-like and PbS-like lattices incommensurability.</p>

Coordinated righting behaviour in locusts

2001 ◽  
Vol 204 (4) ◽  
pp. 637-648 ◽  
Author(s):  
A.A. Faisal ◽  
T. Matheson
Keyword(s):  
Driving Force ◽  
Flat Surface ◽  
Longitudinal Axis ◽  
Upright Position ◽  
The Body ◽  
The Other ◽  
Legged Robots ◽  
Naturally Occurring ◽  
Key Features ◽  
Low Levels

A locust placed upside down on a flat surface uses a predictable sequence of leg movements to right itself. To analyse this behaviour, we made use of a naturally occurring state of quiescence (thanatosis) to position locusts in a standardised upside-down position from which they spontaneously right themselves. Locusts grasped around the pronotum enter a state of thanatosis during which the limbs can be manipulated into particular postures, where they remain, and the animal can be placed upside down on the ground. When released, thanatosis lasts 4–456 s (mean 73 s) before the animal suddenly becomes active again and rights itself within a further 600 ms. Thanatosis is characterised by very low levels of leg motor activity. During righting, one hind leg provides most of the downward force against the ground that rolls the body around a longitudinal axis towards the other side. The driving force is produced by femoral levation (relative to the body) at the trochanter and by tibial extension. As the animal rolls over, the hind leg on the other side is also levated at the trochanter, so that it does not obstruct the movement. The forelegs and middle legs are not required for successful righting but they can help initially to tip the locust to one side, and at the end of the movement they help stop the roll as the animal turns upright. Individual locusts have a preferred righting direction but can, nevertheless, roll to either side. Locusts falling upside down through the air use both passive and active mechanisms to right themselves before they land. Without active movements, falling locusts tend to rotate into an upright position, but most locusts extend their hind leg tibiae and/or spread their wings, which increases the success of mid-air righting from 28 to 49 % when falling from 30 cm. The rapid and reliable righting behaviour of locusts reduces the time spent in a vulnerable upside-down position. Their narrow body geometry, large hind legs, which can generate substantial dorsally directed force, and the particular patterns of coordinated movements of the legs on both sides of the body are the key features that permit locusts to right themselves effectively. The reliability of autonomous multi-legged robots may be enhanced by incorporating these features into their design.

scholarly journals Ligand-Length Modification in CsPbBr3 Perovskite Nanocrystals and Bilayers with PbS Quantum Dots for Improved Photodetection Performance

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1297 ◽  
Author(s):  
Juan Navarro Arenas ◽  
Ananthakumar Soosaimanickam ◽  
Hamid Pashaei Adl ◽  
Rafael Abargues ◽  
Pablo P. Boix ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Surface Chemistry ◽  
Optical Sensors ◽  
Ligand Exchange ◽  
Near Infrared ◽  
Future Internet ◽  
Single Step ◽  
Perovskite Nanocrystals ◽  
Internet Of Things Technology ◽  
Pbs Quantum Dots

Nanocrystals surface chemistry engineering offers a direct approach to tune charge carrier dynamics in nanocrystals-based photodetectors. For this purpose, we have investigated the effects of altering the surface chemistry of thin films of CsPbBr3 perovskite nanocrystals produced by the doctor blading technique, via solid state ligand-exchange using 3-mercaptopropionic acid (MPA). The electrical and electro-optical properties of photovoltaic and photoconductor devices were improved after the MPA ligand exchange, mainly because of a mobility increase up to 5 × 10−3 cm 2 / Vs . The same technology was developed to build a tandem photovoltaic device based on a bilayer of PbS quantum dots (QDs) and CsPbBr3 perovskite nanocrystals. Here, the ligand exchange was successfully carried out in a single step after the deposition of these two layers. The photodetector device showed responsivities around 40 and 20 mA/W at visible and near infrared wavelengths, respectively. This strategy can be of interest for future visible-NIR cameras, optical sensors, or receivers in photonic devices for future Internet-of-Things technology.

scholarly journals Quantitative evaluation of seven optical sensors for cloud microphysical measurements at the Puy-de-Dôme Observatory, France

2015 ◽  
Vol 8 (10) ◽  
pp. 4347-4367 ◽  
Author(s):  
G. Guyot ◽  
C. Gourbeyre ◽  
G. Febvre ◽  
V. Shcherbakov ◽  
F. Burnet ◽  
...  
Keyword(s):  
Optical Properties ◽  
Wind Tunnel ◽  
Optical Sensors ◽  
Wind Direction ◽  
Total Concentration ◽  
Measurement Techniques ◽  
Ambient Air ◽  
Number Concentration ◽  
Effective Diameter ◽  
Particle Volume

Abstract. Clouds have an important role in Earth's radiative budget. Since the late 1970s, considerable instrumental developments have been made in order to quantify cloud microphysical and optical properties, for both airborne and ground-based applications. Intercomparison studies have been carried out in the past to assess the reliability of cloud microphysical properties inferred from various measurement techniques. However, observational uncertainties still exist, especially for droplet size distribution measurements and need to be reduced. In this work, we discuss results from an intercomparison campaign, performed at the Puy de Dôme in May 2013. During this campaign, a unique set of cloud instruments was operating simultaneously in ambient air conditions and in a wind tunnel. A Particle Volume Monitor (PVM-100), a Forward Scattering Spectrometer Probe (FSSP), a Fog Monitor (FM-100), and a Present Weather Detector (PWD) were sampling on the roof of the station. Within a wind tunnel located underneath the roof, two Cloud Droplet Probes (CDPs) and a modified FSSP (SPP-100) were operating. The main objectives of this paper are (1) to study the effects of wind direction and speed on ground-based cloud observations, (2) to quantify the cloud parameters discrepancies observed by the different instruments, and (3) to develop methods to improve the quantification of the measurements. The results revealed that all instruments showed a good agreement in their sizing abilities, both in terms of amplitude and variability. However, some of them, especially the FM-100, the FSSP and the SPP, displayed large discrepancies in their capability to assess the magnitude of the total number concentration of the cloud droplets. As a result, the total liquid water content can differ by up to a factor of 5 between the probes. The use of a standardization procedure, based on data of integrating probes (PVM-100 or visibilimeter) and extinction coefficient comparison substantially enhanced the instrumental agreement. During this experiment, the total concentration agreed in variations with the visibilimeter, except for the FSSP, so a corrective factor can be applied and it ranges from 0.44 to 2.2. This intercomparison study highlights the necessity to have an instrument which provides a bulk measurement of cloud microphysical or optical properties during cloud ground-based campaigns. Moreover, the FM and FSSP orientation was modified with an angle ranging from 30 to 90° angle with wind speeds from 3 to 7 m s−1. The results show that the induced number concentration loss is between 29 and 98 % for the FSSP and between 15 and 68 % for the FM-100. In particular, FSSP experiments showed strong discrepancies when the wind speed was lower than 3 m s−1 and/or when the angle between the wind direction and the orientation of the instruments is greater than 30°. An inadequate orientation of the FSSP towards the wind direction leads to an underestimation of the measured effective diameter.

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