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Topic Review
Aflatoxin
Aflatoxins are poisonous carcinogens that are produced by certain molds (Aspergillus flavus and Aspergillus parasiticus) which grow in soil, decaying vegetation, hay, and grains. They are regularly found in improperly stored staple commodities such as cassava, chili peppers, corn, cotton seed, millet, peanuts, rice, sesame seeds, sorghum, sunflower seeds, tree nuts, wheat, and a variety of spices. When contaminated food is processed, aflatoxins enter the general food supply where they have been found in both pet and human foods, as well as in feedstocks for agricultural animals. Animals fed contaminated food can pass aflatoxin transformation products into eggs, milk products, and meat. For example, contaminated poultry feed is suspected in the findings of high percentages of samples of aflatoxin-contaminated chicken meat and eggs in Pakistan. Children are particularly affected by aflatoxin exposure, which is associated with stunted growth, delayed development, liver damage, and liver cancer. An association between childhood stunting and aflatoxin exposure has been reported in some studies but could not be detected in all. Furthermore, a causal relationship between childhood stunting and aflatoxin exposure has yet to be conclusively shown by epidemiological studies, though such investigations are underway. Adults have a higher tolerance to exposure, but are also at risk. No animal species is immune. Aflatoxins are among the most carcinogenic substances known. After entering the body, aflatoxins may be metabolized by the liver to a reactive epoxide intermediate or hydroxylated to become the less harmful aflatoxin M1. Aflatoxins are most commonly ingested. However the most toxic type of aflatoxin, B1, can permeate through the skin. The United States Food and Drug Administration (FDA) action levels for aflatoxin present in food or feed is 20 to 300 ppb. The FDA has had occasion to declare both human and pet food recalls as a precautionary measure to prevent exposure. The term "aflatoxin" is derived from the name of one of the molds that produce it, Aspergillus flavus. It was coined around 1960 after its discovery as the source of "Turkey X disease". Aflatoxins form one of the major groupings of mycotoxins.
  • 699
  • 28 Oct 2022
Topic Review
AFM imaging of extracellular vesicles
Advanced and optimised microscopy methods, including atomic force microscopy (AFM), are required to visualise and characterise morphology of extracellular vesicles (EVs), a heterogenous groups of nanoparticles regarded as highly promising source of diagnostic, prognostic, and therapeutic tools. EVs are nanosized phospholipid membranous structures ubiquitously found in human biofluids, secreted from almost every cell, and thus reflect both physiological and pathophysiological changes of their parental cells. The lipid membrane of an EV contains proteins (e.g., tetraspanins, receptors and other molecules) and diverse luminal content with bioactive cargo that includes nucleic acids (DNA, mRNA, miRNA and lncRNA), proteins, organelles, or infectious particles.  AFM is a nanoscale tool for the determination of morphology, structure and composition, but also biomechanics and biophysical characteristics of nanometric structures. Briefly, AFM uses a micrometric cantilever with a nanometre-sized tip actuated by piezoelectric crystals. Upon receiving signals of a tip-sample interaction, a position-sensitive photodiode (PSPD) converts it to a voltage and sends it to a piezoelectric actuator (PA). The latter expands and contracts proportionally to the applied voltage to manipulate the sample and the probe position across three dimensions with high precision. The PA can be coupled to a cantilever or positioned under a sample holder. The whole system is controlled by suitable control electronics.
  • 1.4K
  • 11 Oct 2021
Topic Review
Ag2O–MnO2/Graphene Oxide Nanocomposite
Catalytic oxidation of alcohol to their analogous carbonyls is one of the key organic reactions in both scientific and industrial applications, with universal production of 10,000 million tons/year of carbonyls in the 20th century. Such as, aldehyde and ketone derivatives are extensively employed as precursors in insecticide, flame-retardant, cosmetic, confectionery, flavoring, pharmaceutical, and beverage industries. 
  • 1.5K
  • 27 Oct 2020
Topic Review
Agarose Hydrogels
Numerous compounds present in the ocean are contributing to the development of the biomedical field. Agarose, a polysaccharide derived from marine red algae, plays a vital role in biomedical applications because of its reversible temperature-sensitive gelling behavior, excellent mechanical properties, and high biological activity. Natural agarose hydrogel has a single structural composition that prevents it from adapting to complex biological environments.
  • 706
  • 26 May 2023
Topic Review
Agave By-Products
Throughout this review, we have highlighted the current potential of agave by-products as low-cost and natural materials with several applications as biofuels, materials for nanocomposites, and functional ingredients. Among the methods used for by-products processing, US and microwaves are promising and eco-friendly methods for the efficient saccharification and increased digestibility of agave, that can eventually replace chemical processing, reducing waste generation. In this regard, future studies are required concerning accessible, low-cost, and more efficient technologies as a more attractive way for the industry to make a sustainable utilization of this by-product.
  • 575
  • 08 Oct 2021
Topic Review
Aggregation-Induced Emission Active Materials
The emergence and development of aggregation induced emission (AIE) have attracted worldwide attention due to its unique photophysical phenomenon and for removing the obstacle of aggregation-caused quenching (ACQ) which is the most detrimental process thereby making AIE an important and promising aspect in various fields of fluorescent material, sensing, bioimaging, optoelectronics, drug delivery system, and theranostics. hexaphenylsilole (HPS) is the common example of the AIE active molecule which exhibits enhancement in fluorescence in an aggregate state. The motions involved, such as restriction of intramolecular motion along with rotation and vibration mechanisms in the AIE active phenomenon, are well explained and accepted. The AIE luminogens have high photostability, large stoke shift, a photobleaching resistance property, and show high sensing reproducibility. This characteristic makes luminogens a promising candidate for sensing application
  • 1.4K
  • 19 Apr 2022
Topic Review
Aggregation-Induced Emission and Fluorescent Mechanochromism
Mechanochromic fluorescent polymers are defined as materials that are able to detect a mechanical stress through a fluorescence output. This feature has evoked a growing interest in the last decades, thanks to the progress of fluorogenic molecules whose optical characteristics and chemical functionalities allow their effective insertion in many thermoplastic and thermoset matrices. Among the different types of fluorogenic probes able to detect mechanical solicitations, those with aggregation-induced emission (i.e., AIEgens) have attracted tremendous interest since their discovery in 2001. In this contribution, the main principles behind the AIEgens working behavior are introduced along with the current state of knowledge concerning the design and preparation of the derived mechanochromic fluorescent polymers. Examples are provided concerning the most ingenious solution for the preparation of chromogenic materials, starting from dierent types of commodity plastics or synthetic polymers and combined with the latest AIE technology to provide the most sensitive response to mechanical stress.
  • 2.8K
  • 30 Oct 2020
Topic Review
Aggregation-Induced Emission Properties in Polymers
Aggregation-Induced Emission (AIE) is a phenomenon that consists of the appearance of fluorescence in solid state or aggregation greater than that of molecules in solution and has recently attracted the attention of the scientific community because of their potential applications in different fields. Compared to small molecules, little attention has been paid to polymers and oligomers that exhibit AIE, despite having excellent properties such as high emission efficiency in aggregate and solid states, signal amplification effect, good processability and the availability of multiple functionalization sites. In addition to these features, if the molecular structure is fully conjugated, intramolecular electronic interactions between the composing chromophores may appear, thus giving rise to a wealth of new photophysical properties. In this review, we focus on selected fully conjugated oligomers, dendrimers and polymers, and briefly summarize their synthetic routes, fluorescence properties and potential applications. An exhaustive comparison between spectroscopic results in solution and aggregates or in solid state has been collected in almost all examples, and an opinion on the future direction of the field is briefly stated.
  • 705
  • 02 Feb 2021
Topic Review
Aging Performance of Polymer-Modified Binders
The term “aging of polymer-modified binder”, as well as the term “bitumen aging” in a generalized form, combines the whole set of reversible and irreversible changes in its chemical composition, physical transformations, and changes in structural and mechanical properties occurring during the production of polymer-modified binders, its storage/transportation, technological processing, and operation, i.e., during the entire lifecycle of the polymer-modified binder. Polymer-modified binders are complex multicomponent systems in which polymer and other additives, if available, make a significant contribution to the aging process.
  • 194
  • 15 Dec 2023
Topic Review
AgNPs
Elementary silver nanoparticles (AgNPs) are of great interest because of their various probable medical application. Due to their antimicrobial activity, low toxicity and inexpensive cost, the mechanism of silver nanoparticles biosynthesis in bacterial, fungal and plant cells is extremely exciting from the point of view of the different cellular compounds participation in it: proteins, enzymes, acids, etc.
  • 2.3K
  • 15 Dec 2020
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