synthetic approach
Recently Published Documents





Toxins ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 56
Justin B. Renaud ◽  
Jacob P. Walsh ◽  
Mark W. Sumarah

Aflatoxins B1 (AFB1) and G1 (AFG1) are carcinogenic mycotoxins that contaminate crops such as maize and groundnuts worldwide. The broadly accepted method to assess chronic human aflatoxin exposure is by quantifying the amount of aflatoxin adducted to human serum albumin. This has been reported using ELISA, HPLC, or LC-MS/MS to measure the amount of AFB1-lysine released after proteolysis of serum albumin. LC-MS/MS is the most accurate method but requires both isotopically labelled and unlabelled AFB1-lysine standards, which are not commercially available. In this work, we report a simplified synthetic route to produce unlabelled, deuterated and 13C6 15N2 labelled aflatoxin B1-lysine and for the first-time aflatoxin G1-lysine. Additionally, we report on the stability of these compounds during storage. This simplified synthetic approach will make the production of these important standards more feasible for laboratories performing aflatoxin exposure studies.

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 609
Roman Meshcheryakov ◽  
Andrey Iskhakov ◽  
Mark Mamchenko ◽  
Maria Romanova ◽  
Saygid Uvaysov ◽  

The paper proposes an approach to assessing the allowed signal-to-noise ratio (SNR) for light detection and ranging (LiDAR) of unmanned autonomous vehicles based on the predetermined probability of false alarms under various intentional and unintentional influencing factors. The focus of this study is on the relevant issue of the safe use of LiDAR data and measurement systems within the “smart city” infrastructure. The research team analyzed and systematized various external impacts on the LiDAR systems, as well as the state-of-the-art approaches to improving their security and resilience. It has been established that the current works on the analysis of external influences on the LiDARs and methods for their mitigation focus mainly on physical (hardware) approaches (proposing most often other types of modulation and optical signal frequencies), and less often software approaches, through the use of additional anomaly detection techniques and data integrity verification systems, as well as improving the efficiency of data filtering in the cloud point. In addition, the sources analyzed in this paper do not offer methodological support for the design of the LiDAR in the very early stages of their creation, taking into account a priori assessment of the allowed SNR threshold and probability of detecting a reflected pulse and the requirements to minimize the probability of “missing” an object when scanning with no a priori assessments of the detection probability characteristics of the LiDAR. The authors propose a synthetic approach as a mathematical tool for designing a resilient LiDAR system. The approach is based on the physics of infrared radiation, the Bayesian theory, and the Neyman–Pearson criterion. It features the use of a predetermined threshold for false alarms, the probability of interference in the analytics, and the characteristics of the LiDAR’s receivers. The result is the analytical solution to the problem of calculating the allowed SNR while stabilizing the level of “false alarms” in terms of background noise caused by a given type of interference. The work presents modelling results for the “false alarm” probability values depending on the selected optimality criterion. The efficiency of the proposed approach has been proven by the simulation results of the received optical power of the LiDAR’s signal based on the calculated SNR threshold and noise values.

Pogisego Dinake ◽  
Gothatamang Norma Phokedi ◽  
Janes Mokgadi ◽  
Anthony Ntshekisang ◽  
Mmamiki Ayanda Botlhomilwe ◽  

Latent fingerprint detection and visualization remains a challenge especially where problems of poor contrast, auto-fluorescent surfaces and patterned backgrounds are encountered. As a result there is an increasing interest in the development of simple, cost effective, rapid and yet accurate methods for latent fingerprint detection and recovery. Herein, this paper reports the synthesis of bright blue photoluminescent carbon dots (C-dots) via an eco-friendly and simple one-step microwave-assisted carbonization of potato peels’ biomass. The C-dots were prepared in only 3 min and ground into powder and used without any further treatment. The as-prepared C-dots were characterized using atomic force microscope, Fourier transform infra-red spectroscopy and X-ray diffraction with an average size of 1.0[Formula: see text]nm. The optical properties of the as-prepared C-dots were studied by UV-Vis spectroscopy and spectrofluorometer which established an excitation and emission wavelengths of 390[Formula: see text]nm and 480[Formula: see text]nm, respectively. Owing to their strong solid state fluorescence, the as-prepared C-dots’ powder was successfully used in latent fingerprint detection and imaging on porous and nonporous surfaces. Latent fingerprints were recovered with high resolution and excellent quality providing sufficient details for individual identification. These findings demonstrate that C-dots derived from biomass have a great potential in latent fingerprint analysis for forensic applications.

2022 ◽  
Vol 9 ◽  
Angel Green Samuel ◽  
Sowmya Subramanian ◽  
Vijaikanth Vijendran ◽  
Jebasingh Bhagavathsingh

We report stable and heterogeneous graphene oxide (GO)–intercalated copper as an efficient catalyst for the organic transformations in green solvents. The GO-intercalated copper(II) complex of bis(1,4,7,10-tetraazacyclododecane) [Cu(II)-bis-cyclen] was prepared by a facile synthetic approach with a high dilution technique. The as-prepared GO-Cu(II)-bis-cyclen nanocomposite was used as a click catalyst for the 1,3 dipolar Huisgen cycloaddition reaction of terminal alkyne and azide substrates. On directing a great deal of attention toward the feasibility of the rapid electron transfer rate of the catalyst in proliferating the yield of 1,2,3-triazole products, the click catalyst GO-Cu(II)-bis-cyclen nanocomposite was designed and synthesized via non-covalent functionalization. The presence of a higher coordination site in an efficient 2D nanocomposite promotes the stabilization of Cu(I) L-acetylide intermediate during the catalytic cycle initiated by the addition of reductants. From the XRD analysis, the enhancement in the d-interlayer spacing of 1.04 nm was observed due to the intercalation of the Cu(II)-bis-cyclen complex in between the GO basal planes. It was also characterized by XPS, FT-IR, RAMAN, UV, SEM, AFM, and TGA techniques. The recyclability of the heterogeneous catalyst [GO-Cu(II)-cyclen] with the solvent effect has also been studied. This class of GO-Cu(II)-bis-cyclen nanocomposite paves the way for bioconjugation of macromolecules through the click chemistry approach.

Synthesis ◽  
2022 ◽  
Chuan He ◽  
Wei Yuan

In recent years, transition-metal-catalyzed enantioselective C–H bond functionalization has emerged as a powerful and attractive synthetic approach to access silicon-stereogenic centers, which continues to give impetus for the innovation of chiral organosilicon chemistry. This short review is aimed to summarize recent advances in the construction of silicon-stereogenic silanes via transition-metal-catalyzed enantioselective C–H functionalization. We have endeavored to highlight the great potential of this methodology and hope that this review will shed light on new perspectives, inspire further research in this emerging area.

2021 ◽  
Vol 68 (6) ◽  
pp. 1-47
Jonathan Sterling ◽  
Robert Harper

The theory of program modules is of interest to language designers not only for its practical importance to programming, but also because it lies at the nexus of three fundamental concerns in language design: the phase distinction , computational effects , and type abstraction . We contribute a fresh “synthetic” take on program modules that treats modules as the fundamental constructs, in which the usual suspects of prior module calculi (kinds, constructors, dynamic programs) are rendered as derived notions in terms of a modal type-theoretic account of the phase distinction. We simplify the account of type abstraction (embodied in the generativity of module functors) through a lax modality that encapsulates computational effects, placing projectibility of module expressions on a type-theoretic basis. Our main result is a (significant) proof-relevant and phase-sensitive generalization of the Reynolds abstraction theorem for a calculus of program modules, based on a new kind of logical relation called a parametricity structure . Parametricity structures generalize the proof-irrelevant relations of classical parametricity to proof- relevant families, where there may be non-trivial evidence witnessing the relatedness of two programs—simplifying the metatheory of strong sums over the collection of types, for although there can be no “relation classifying relations,” one easily accommodates a “family classifying small families.” Using the insight that logical relations/parametricity is itself a form of phase distinction between the syntactic and the semantic, we contribute a new synthetic approach to phase separated parametricity based on the slogan logical relations as types , by iterating our modal account of the phase distinction. We axiomatize a dependent type theory of parametricity structures using two pairs of complementary modalities (syntactic, semantic) and (static, dynamic), substantiated using the topos theoretic Artin gluing construction. Then, to construct a simulation between two implementations of an abstract type, one simply programs a third implementation whose type component carries the representation invariant.

2021 ◽  
Vol 42 (1) ◽  
Uroš Kranjc

The young Marx once remarked that political economy finds itself in an estranged form and is therefore in desperate need of a critical reconstruction of its object [Gegenstand]. He proposed a complete deconstruction of economic objectivity and its categories, hoping to recover the true species-life of man. In the article, we assert that contemporary economic theory remains confined by this estrangement, despite managing to ‘revolutionize’ itself out of the grip of classical political economy. The subjectivist-marginalist reliance on ‘measurable’ consumer preferences not only solidified the discipline’s estrangement, but also wrested away any remaining basic principles of economics through neoclassical reconceptualization. A break with estrangement would require novel critical economic thinking that would do away with the discontinuity between classical and neoclassical (contemporary) economics. It would therefore need a rich enough framework to scrutinize its principal categories. We argue that Alain Badiou’s objective phenomenology possesses a complementary synchronic structure able to conform to basic economic tenets, allowing for a comparative and synthetic approach. This would then be the basis for a new model of economic theorizing. We conclude the article with Marx’s value form, seeing it as a possible central category of a newly proposed economic framework.

2021 ◽  
Vol 18 (2) ◽  
pp. 71-84
Omid Amani ◽  
Hossein Pirnajmuddin ◽  
Ghiasuddin Alizadeh

Sam Shepard’s Cowboys #2 (1967) belongs to his first period of play writing. In this phase, his works exhibit experimental, remote, impossible narrative/fictional worlds that are overwhelmingly abstract, exhibiting “abrupt shifts of focus and tone” (Wetzsteon 1984, 4). Shepard’s unusual theatrical literary cartography is commensurate with his depiction of unnatural temporalities, in that, although the stage is bare, with almost no props, the postmodernist/metatheatrical conflated timelines and projected (impossible) places in the characters’ imagination mutually reflect and inflect each other. Employing Jan Alber’s reading strategies in his theorization of unnatural narratology and Barbara Piatti’s concept of projected places, this essay proposes a synthetic approach so as to naturalize the unnatural narratives and storyworlds in Shepard’s play.

2021 ◽  
N. V. Sergienko ◽  
N. V. Polshchikova ◽  
M. I. Buzin ◽  
V. M. Kotov ◽  

A novel synthetic approach to the block copolymers bearing diorganosiloxane and organosilsesquioxane blocks is suggested that obviates the need for using organochlorosilane precursors. A series of the polymers with different combinations of oligodimethylsiloxane and oligomethylphenylsiloxane flexible blocks with methylsilsesquioxane and phenylsilsesquioxane rigid blocks is prepared. The thermal properties of the films obtained from these polymers are explored.

Sign in / Sign up

Export Citation Format

Share Document