Photochromic dyes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Andrew Towns

Abstract This article describes the defining characteristics of photochromic dyes and highlights the subset of properties that are of greatest commercial importance. It outlines the history of the industrial exploitation of photochromic colorants before moving on to discuss current and potential applications. In doing so, a brief tour of key types of photochromic dye is provided.

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Shixin Deng ◽  
Brett J. West ◽  
'Afa K. Palu ◽  
C. Jarakae Jensen

Noni blossoms have a long history of medicinal uses in tropical areas. This study was conducted to investigate the major phytochemical components, toxicological properties, and antioxidant activity of noni blossoms. An HPLC-PDA method was developed and validated for the identification and quantification of major components. The major phytochemicals were iridoid glycosides, deacetylasperulosidic acid and asperulosidic acid, and flavonoids, quercetin-3-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside and kaempferol-3-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside, each present at 3.764, 3.576, 1.513, and 3.096 mg/g, respectively. The aqueous extract of noni blossoms, at 500 μg/mL, exhibited greater antioxidant activity in the 2,2-diphenylpicrylhydrazyl radical scavenging assay than green tea (88.11 ± 0.01% versus 76.60 ± 0.05%). A primary DNA damage test in E. coli PQ37 (SOS-chromotest) and a twenty-four hour brine shrimp toxicity test did not reveal any genotoxic or cytotoxic activity. These results provide a useful reference for the identification of noni blossoms as well as preliminary evaluation of safety and efficacy. Further evaluation of the potential applications of noni blossoms is warranted.


2020 ◽  
Vol 5 (7) ◽  
Author(s):  
Andrew Towns

AbstractThis article introduces the general characteristics of the diarylethene class of photochromic dye and the structural features that make photochromism possible. It touches on the methodologies employed to synthesize these compounds as well as the influences that typical substitution patterns exert on photocoloration. A demonstration is then given of the great diversity pertaining to the potential applications in which researchers are seeking to exploit them as functional colorants.


2021 ◽  
Author(s):  
Thomas Theurer ◽  
David Muirhead ◽  
David Jolley ◽  
Dmitri Mauquoy

<p>Raman spectroscopy represents a novel methodology of characterising plant-fire interactions through geological history, with enormous potential. Applications of Raman spectroscopy to charcoal have shown that this is an effective method of understanding intensity changes across palaeofire regimes. Such analyses have relied on the determination of appropriate Raman parameters, given their relationship with temperature of formation and microstructural changes in reference charcoals. Quantitative assessments of charcoal microstructure have also been successfully applied to the assessment of carbonaceous maturation under alternate thermal regimes, such as pyroclastic volcanism. Palaeowildfire systems in association with volcanism may present a complex history of thermal maturation, given interactions between detrital charcoals and volcanogenic deposition. However, whilst palaeofire and volcanic maturation of carbonaceous material are well understood individually, their interaction has yet to be characterised. Here we present the first analysis of palaeofire charcoals derived from volcanic ignition utilising Raman spectroscopy. Our results indicate that complex interactions between volcanism and palaeofire systems may be better understood by the characterisation of charcoal microstructure, alongside palaeobotanical and ecosystem studies. Understanding the unique relationship between wildfires and volcanism, and the impact that this has on the fossil record, may better assist our understanding of wildfire systems in deep history. Further still, this highlights the potential for better understanding the socioecological impacts of modern and future wildfire systems closely associated with volcanic centres. </p>


2014 ◽  
Vol 11 (100) ◽  
pp. 20140834 ◽  
Author(s):  
Xiao-Yong Yan ◽  
Chen Zhao ◽  
Ying Fan ◽  
Zengru Di ◽  
Wen-Xu Wang

Despite the long history of modelling human mobility, we continue to lack a highly accurate approach with low data requirements for predicting mobility patterns in cities. Here, we present a population-weighted opportunities model without any adjustable parameters to capture the underlying driving force accounting for human mobility patterns at the city scale. We use various mobility data collected from a number of cities with different characteristics to demonstrate the predictive power of our model. We find that insofar as the spatial distribution of population is available, our model offers universal prediction of mobility patterns in good agreement with real observations, including distance distribution, destination travel constraints and flux. By contrast, the models that succeed in modelling mobility patterns in countries are not applicable in cities, which suggests that there is a diversity of human mobility at different spatial scales. Our model has potential applications in many fields relevant to mobility behaviour in cities, without relying on previous mobility measurements.


The discovery of enzymes with lipolytic activities in all kingdoms of life from prokaryote to eukaryote species raises the possibility of the presence of an evolutionary relationship history of these proteins among many species of various living organisms. The chapter suggests a strategy based on the phylogenetic distribution and homology conservation in plant lipolytic enzymes for possible depiction of their biological evolution. Extensive databases and online resources for lipidomics and related areas are useful tools to analyze the different lipolytic enzymes in the three major super kingdoms of life, including higher plants kingdom and confined organisms such as algae that have recently gained much interest due to their promising potential applications in lipids hydrolysis and biosynthesis. Multiple sequence alignments of the identified lipolytic enzymes from databases could serve to the identification of globally conserved residues as well as conserved sequence motifs. Estimation of evolutionary distance between the various identified lipolytic enzymes could also be carried out to better understand the pattern of evolution.


Author(s):  
Ryuichi Murase ◽  
Bowen Ding ◽  
Qinyi Gu ◽  
Deanna M. D'Alessandro

Electroactive and conducting framework materials, encompassing coordination polymers and metal–organic frameworks, have captured the imagination of the scientific community owing to their highly designable nanoporous structures and their potential applications in electrochromic devices, electrocatalysts, porous conductors, batteries and solar energy harvesting systems, among many others. While they are now considered integral members of the broader field of inorganic materials, it is timely to reflect upon their strengths and challenges compared with ‘traditional’ solid-state materials such as minerals, pigments and zeolites. Indeed, the latter have been known since ancient times and have been prized for centuries in fields as diverse as art, archaeology and industrial catalysis. This opinion piece considers a brief historical perspective of traditional electroactive and conducting inorganic materials, with a view towards very recent experimental progress and new directions for future progress in the burgeoning area of coordination polymers and metal–organic frameworks. Overall, this article bears testament to the rich history of electroactive solids and looks at the challenges inspiring a new generation of scientists. This article is part of the theme issue ‘Mineralomimesis: natural and synthetic frameworks in science and technology’.


2011 ◽  
Vol 435 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Charles S. Craik ◽  
Michael J. Page ◽  
Edwin L. Madison

Proteases are an expanding class of drugs that hold great promise. The U.S. FDA (Food and Drug Administration) has approved 12 protease therapies, and a number of next generation or completely new proteases are in clinical development. Although they are a well-recognized class of targets for inhibitors, proteases themselves have not typically been considered as a drug class despite their application in the clinic over the last several decades; initially as plasma fractions and later as purified products. Although the predominant use of proteases has been in treating cardiovascular disease, they are also emerging as useful agents in the treatment of sepsis, digestive disorders, inflammation, cystic fibrosis, retinal disorders, psoriasis and other diseases. In the present review, we outline the history of proteases as therapeutics, provide an overview of their current clinical application, and describe several approaches to improve and expand their clinical application. Undoubtedly, our ability to harness proteolysis for disease treatment will increase with our understanding of protease biology and the molecular mechanisms responsible. New technologies for rationally engineering proteases, as well as improved delivery options, will expand greatly the potential applications of these enzymes. The recognition that proteases are, in fact, an established class of safe and efficacious drugs will stimulate investigation of additional therapeutic applications for these enzymes. Proteases therefore have a bright future as a distinct therapeutic class with diverse clinical applications.


2018 ◽  
pp. 1-11 ◽  
Author(s):  
Çağlar Çağlayan ◽  
Hiromi Terawaki ◽  
Qiushi Chen ◽  
Ashish Rai ◽  
Turgay Ayer ◽  
...  

Purpose Microsimulation is a modeling technique that uses a sample size of individual units (microunits), each with a unique set of attributes, and allows for the simulation of downstream events on the basis of predefined states and transition probabilities between those states over time. In this article, we describe the history of the role of microsimulation in medicine and its potential applications in oncology as useful tools for population risk stratification and treatment strategy design for precision medicine. Methods We conducted a comprehensive and methodical search of the literature using electronic databases—Medline, Embase, and Cochrane—for works published between 1985 and 2016. A medical subject heading search strategy was constructed for Medline searches by using a combination of relevant search terms, such as “microsimulation model medicine,” “multistate modeling cancer,” and “oncology.” Results Microsimulation modeling is particularly useful for the study of optimal intervention strategies when randomized control trials may not be feasible, ethical, or practical. Microsimulation models can retain memory of prior behaviors and states. As such, it allows an explicit representation and understanding of how various processes propagate over time and affect the final outcomes for an individual or in a population. Conclusion A well-calibrated microsimulation model can be used to predict the outcome of the event of interest for a new individual or subpopulations, assess the effectiveness and cost effectiveness of alternative interventions, and project the future disease burden of oncologic diseases. In the growing field of oncology research, a microsimulation model can serve as a valuable tool among the various facets of methodology available.


2009 ◽  
Vol 74 (1) ◽  
pp. 143-172 ◽  
Author(s):  
James B. Benedict

Lichenometry—a method developed by geologists for dating Holocene moraines and other landforms—has many potential applications in archaeology. Maximum-diameter lichenometry can suggest ages for features that were initially lichen-free, such as the moai of Easter Island, and rock surfaces exposed by toolstone quarrying. Size-frequency analysis can provide dates for structures built of lichen-covered rocks, such as game-drive walls and blinds, meat caches, and tent rings. Both methods require local calibration curves, best constructed by measuring lichens on substrata of known exposure age. Most lichenometric studies have involved yellow members of the crustose genus Rhizocarpon, which grow slowly and can live for as long as 10,000 years. Lichenometry has been particularly successful on siliceous rock types in arctic, subarctic, and alpine-tundra environments. The effects of wildfire and of competition from foliose lichens make the technique less well suited for forested terrain. Few data are available for tropical or desert environments or for calcareous substrata. The reliability of a lichenometric date will depend on the quality of the calibration curve, the size of the sample, the nature and postoccupational history of the substratum, and the ability of the archaeologist to recognize potential disturbance factors. An ecological perspective is essential. Known archaeological applications and problems are discussed.


Acta Numerica ◽  
2006 ◽  
Vol 15 ◽  
pp. 257-325 ◽  
Author(s):  
Emmanuel J. Candès

A number of fundamental results in modern statistical theory involve thresholding estimators. This survey paper aims at reconstructing the history of how thresholding rules came to be popular in statistics and describing, in a not overly technical way, the domain of their application. Two notions play a fundamental role in our narrative: sparsity and oracle inequalities. Sparsity is a property of the object to estimate, which seems to be characteristic of many modern problems, in statistics as well as applied mathematics and theoretical computer science, to name a few. ‘Oracle inequalities’ are a powerful decision-theoretic tool which has served to understand the optimality of thresholding rules, but which has many other potential applications, some of which we will discuss.Our story is also the story of the dialogue between statistics and applied harmonic analysis. Starting with the work of Wiener, we will see that certain representations emerge as being optimal for estimation. A leitmotif throughout our exposition is that efficient representations lead to efficient estimation.


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