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1.
Appl Spectrosc ; : 37028241267920, 2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-39090839

RESUMEN

Growing demand for pesticides has created an environment prone to deceptive activities, where counterfeit or adulterated pesticide products infiltrate the market, often escaping rapid detection. This situation presents a significant challenge for sensor technology, crucial in identifying authentic pesticides and ensuring agricultural safety practices. Raman spectroscopy emerges as a powerful technique for detecting adulterants. Coupling the electrochemical techniques allows a more specific and selective detection and compound identification. In this study, we evaluate the efficacy of spectroelectrochemical measurements by coupling a potentiostat and Raman spectrograph to identify paraquat, a nonselective herbicide banned in several countries. Our findings demonstrate that applying -0.70 V during measurements yields highly selective Raman spectra, highlighting the primary vibrational bands of paraquat. Moreover, the selective Raman signal of paraquat was discernible in complex samples, including tap water, apple, and green cabbage, even in the presence of other pesticides such as diquat, acephate, and glyphosate. These results underscore the potential of this technique for reliable pesticide detection in diverse and complex matrices.

2.
Front Med (Lausanne) ; 11: 1429872, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39091292

RESUMEN

Background: Falsified medicines and their international regulation impacts all healthcare sectors and their actors. These regulations aim to strengthen and protect the global pharmaceutical supply chain against falsified medicines. However, an evaluation of the impacts of these regulations on key stakeholders within the legitimate supply chain have not been explored. Objective: This research aimed to evaluate both the positive and negative impacts of falsified medicines regulation on key stakeholders within the global pharmacy sector including including manufacturers, wholesalers, hospital pharmacies, community pharmacy and patients. Design: This research consists of a systematic review and thematic analysis concerning falsified medicines regulation and the subsequent impacts of existing global regulations on healthcare. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and checklist were utilized for reporting in this systematic review. Data sources and methods: A search of three databases, Embase, ProQuest and PubMed, was undertaken to determine studies applicable to the research question. The Mixed Methods Appraisal Tool (MMAT) was used to assess methodological quality and risk of bias for all included studies. Results: From the initial 657 studies, a final set of 13 relevant studies were identified. The most frequently reported falsified medicines regulation was the Falsified Medicines Directive (FMD) [n = 11]. The impact of falsified medicines regulation in the literature related to four areas: (1) Financial, (2) Social, (3) Organizational, and (4) Pharmacy Practice. These common themes across the included studies frequently relate to challenges and/or concerns associated with falsified medicines regulation implementation as well as both the logistics and practicality of incorporating falsified medicines regulations into daily operations. Conclusion: Implementation and enforcement of falsified medicines regulation does not yet appear to categorically fulfill the primary aim of the regulations, to strengthen the drug supply chain. However, in recent years, such regulations have challenged the legitimate pharmaceutical supply change actors as they attempt to successfully implement these regulations. Studies mainly detail the negative impacts of regulation during the implementation phase but with the overall benefit pertaining to the prioritization and enhancement of patient care and safety within the healthcare sector.

3.
Clin Case Rep ; 12(8): e9241, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39114837

RESUMEN

When self-administration with counterfeit or mislabeled medicine is suspected, comprehensive laboratory analysis should be preferred over immunoassay screening to avoid false negative results. Carisoprodol, which was formerly a popular muscle relaxant drug in many countries, has reappeared on illegal drug markets, and may cause an itching, purple-colored rash, even after a single dose.

4.
Front Psychol ; 15: 1394660, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39100560

RESUMEN

Introduction: As a globally prevalent phenomenon, buying counterfeit products harms consumers, economies, societies, governments, and the environment. The study examined the hierarchy of injunctive normative influence (personal vs. societal) on counterfeit purchase intentions and trends in non-deceptive (known) counterfeit purchase behavior. The current research expands the hierarchical norms approach by examining how the cultural values of power distance and individualism-collectivism predict injunctive normative perceptions and counterfeit buying intention and behavior. Methods: A cross-sectional survey (N = 13,053) of consumers from 17 nations, administered in seven languages, explored cross-country differences in perceived social norms about buying counterfeits. Results: The findings of multilevel moderated mediation analyses showed that personal injunctive norms (perceived acceptance of buying counterfeits by close friends) mediated the relationship between societal injunctive norms (perceived acceptance for buying counterfeits by peers in the same country) and the outcome variables. Selected paths of the mediation model were moderated by the two cultural dimensions. Discussion: Theoretical implications are discussed within the context of cultural orientations' and social norms' roles in informing risky behavior, and practically, within the context of awareness-raising and behavior-change interventions.

5.
Molecules ; 29(15)2024 Jul 28.
Artículo en Inglés | MEDLINE | ID: mdl-39124967

RESUMEN

The development of new methods of identification of active pharmaceutical ingredients (API) is a subject of paramount importance for research centers, the pharmaceutical industry, and law enforcement agencies. Here, a system for identifying and classifying pharmaceutical tablets containing acetaminophen (AAP) by brand has been developed. In total, 15 tablets of 11 brands for a total of 165 samples were analyzed. Mid-infrared vibrational spectroscopy with multivariate analysis was employed. Quantum cascade lasers (QCLs) were used as mid-infrared sources. IR spectra in the spectral range 980-1600 cm-1 were recorded. Five different classification methods were used. First, a spectral search through correlation indices. Second, machine learning algorithms such as principal component analysis (PCA), support vector classification (SVC), decision tree classifier (DTC), and artificial neural network (ANN) were employed to classify tablets by brands. SNV and first derivative were used as preprocessing to improve the spectral information. Precision, recall, specificity, F1-score, and accuracy were used as criteria to evaluate the best SVC, DEE, and ANN classification models obtained. The IR spectra of the tablets show characteristic vibrational signals of AAP and other APIs present. Spectral classification by spectral search and PCA showed limitations in differentiating between brands, particularly for tablets containing AAP as the only API. Machine learning models, specifically SVC, achieved high accuracy in classifying AAP tablets according to their brand, even for brands containing only AAP.


Asunto(s)
Acetaminofén , Aprendizaje Automático , Análisis de Componente Principal , Espectrofotometría Infrarroja , Comprimidos , Acetaminofén/química , Acetaminofén/análisis , Comprimidos/química , Espectrofotometría Infrarroja/métodos , Redes Neurales de la Computación , Algoritmos , Máquina de Vectores de Soporte
6.
Small Methods ; : e2400447, 2024 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-39115353

RESUMEN

Various fascinating optical characteristics in organisms encourage scientists to develop biomimetic synthesis strategies and mimic their unique microstructure. Inspired by the Chameleon's skin with tunable color and superior flexibility, this work designs the evaporated-induced self-assembly technique to synthesize the chiral photonic crystal film. Ultrasonic-intensified and additive-assisted techniques synergistically optimize the film properties, on the aspects of optic and mechanic. The film shows considerable rigidity and superior flexibility, which can undergo multiple mechanical deformations. Without destroying the chiral nematic structure, the ultimate strain approaches 50%, which exceeds most cellulose-derived film materials. It also integrates excellent optical performance. The film color can cover the total visible region by tuning the photonic bandgap and has angle-dependent properties. It can make the response to humidity and solvents, and chromaticity variation reflects the degree of stimulation. Importantly, this structural-dependent color change is reversible. Lastly, the photonic crystal materials with excellent mechanics and unique optics have been applied in the security. The anti-counterfeiting material design contains photonic crystal ink, repeatable writing paper, information-hiding film, and color-changing labels, with the features of environmentally friendly, economical, non-destructive, and convenient for authentication.

7.
J Pharm Policy Pract ; 17(1): 2375267, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39015754

RESUMEN

Background: Substandard, falsified, unlicensed, and unregistered medicines pose significant risks to public health in developed and developing countries. This systematic review provides an overview of the prevalence of substandard, falsified, unlicensed, and unregistered medicine and its associated factors in Africa. Methods: Articles published from April 2014 to March 2024 were searched in Google Scholar, Science Direct, PubMed, MEDLINE, and Embase. The search strategy focused on open-access articles published in peer-reviewed scientific journals and studies exclusively conducted in African countries. The quality of the studies was assessed according to the Medicine Quality Assessment Reporting Guidelines (MEDQUARG). This systematic review was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Results: Of the 27 studies, 26 had good methodological quality after a quality assessment. Of the 7508 medicine samples, 1639 failed at least one quality test and were confirmed to be substandard/falsified medicines. The overall estimated prevalence of substandard/falsified medicines in Africa was 22.6% (1718/7592). The average prevalence of unregistered medicines was 34.6% (108/312). Antibiotics, antimalarial, and antihypertensive medicines accounted for 44.6% (712/1596), 15.6% (530/3530), 16.3% (249/1530), and 16.3% (249/1530), respectively. Approximately 60.7% (91/150) were antihelmintic and antiprotozoal medicines. Poor market regulatory permission, Free trade zones, poor registration, high demand, and poor importation standards contribute to the prevalence of these problems. Conclusion/Recommendations: Substandard, falsified, and unregistered medicines are highly prevalent in Africa, and attention has not been paid to the problem. Antibiotics, antimalarial, anthelmintic, and antiprotozoal are the most commonly reported substandard, falsified, and unregistered medicines. A consistent supply of high-quality products, enhancement of registration, market regulatory permission, and importation standards are essential to counter the problems in Africa. Preventing these problems is the primary duty of every responsible nation to save lives.

8.
BMC Public Health ; 24(1): 2040, 2024 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-39080671

RESUMEN

Food fraud (often called fake food in South Africa) the deliberate misrepresentation or adulteration of food products for financial gain, is a growing problem in South Africa (SA) with severe public health and financial consequences for consumers and businesses. The recent public outcry against food fraud practices especially in communities that have lost loved ones due to the consumption of allegedly adulterated foodstuffs, highlights the grave danger that food fraud poses to consumers and the potential for significant reputational damage to food manufacturers. Despite the risks, food fraud often goes undetected, as perpetrators are becoming increasingly sophisticated. The precise magnitude of food fraud remains obscure, as incidents that do not cause consumer illnesses are frequently unreported and, as a result, are not investigated. Food fraud costs the global economy billion annually. This cost is borne by consumers, businesses, and the government. Food fraud can occur at any stage of the food supply chain, from production to processing to retailing or distribution. This is due in part to the limitations of current analytical methods, which are not always able to detect food fraud. This review of food fraud in SA looks at several factors that may be contributing to epidemic of food fraud, including inadequate penalties, inadequate government commitment, a complex labelling regulation, emerging threats such as e-commerce, and shortage of inspectors and laboratories. The review recommends establishing a single food control/safety authority, developing more food safety laboratories, and adopting innovative technologies to detect and prevent food fraud. SA faces a serious food fraud crises unless decisive action is taken.


Asunto(s)
Inocuidad de los Alimentos , Fraude , Sudáfrica , Humanos , Fraude/prevención & control , Salud Ambiental , Contaminación de Alimentos/análisis
9.
Curr Pharm Teach Learn ; 16(10): 102140, 2024 Jul 12.
Artículo en Inglés | MEDLINE | ID: mdl-39002340

RESUMEN

INTRODUCTION: The circulation of substandard and counterfeit pharmaceutical products on the national and international markets has increased. Different studies revealed that there is limited information about pharmacy professionals' awareness of substandard and counterfeit pharmaceutical products. Therefore; the aim of the present study was to assess the pharmacy professionals' knowledge, attitude, and practice of substandard and counterfeit pharmaceutical products. METHODS: A cross-sectional study was conducted to assess the knowledge, attitude, and practice of pharmacy professionals about substandard and counterfeited pharmaceutical products in Gondar City, North-West Ethiopia. Data were collected through a self-administered, structured questionnaire using the Kobo tool. SPSS version 27 was used for the analysis. To assess the association of factors with pharmacy professionals' practice towards substandard and counterfeit medicines, we conducted univariate and multivariate logistic regression analysis. RESULTS: A total of 170 respondents participated in the study. The highest numbers of participants (71.8%) were in the age group of 18-30 years. Only 10.6% of them reported purchasing medicines regularly. Of total, 31 (18.24%) of respondents had a good knowledge and more than one-third 60 (35.29%) of the respondents had a good level of practice. Multivariate logistic regression analysis results revealed that some socio-demography and attitude (AOR = 0.473 (0.225-0.995) were associated with the practice of pharmacy professionals towards substandard and counterfeit medicines. CONCLUSION: In general, less than one-quarters of the respondents had a good knowledge and more than one-thirds of the respondents had a good level of practice. However, half of the respondents had a positive attitude.

10.
BMC Public Health ; 24(1): 1564, 2024 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-38862992

RESUMEN

BACKGROUND: Smuggling health goods given the importance and critical nature of health services should be undeniably addressed and controlled by all countries. This issue is especially more widespread in developing countries with more damaging consequences. This paper therefore aims to identify and analyze the challenges of preventing smuggling of health goods in Iran. METHOD: Within this qualitative study, we conducted face-to-face, semi-structured interviews with 30 purposefully recruited key informants and stakeholders in the detection, prevention, and combating of health goods smuggling. Each interview was analyzed thematically, using an inductive approach to generate codes, then categorized and presented in the form of main themes and sub-themes. Maxqda 11 assisted in coding, analysis, and data management. RESULTS: Three main themes emerged representing the challenges of prevention of smuggling in Iran in the areas of anti-smuggling policy development, including categories of inefficient policy and plan, and failure to reach agenda; policy implementation; categorized into actors, resources and instruments, and implementation guarantee; and finally monitoring and evaluation; including, procedures and practices, and the role of surveyors. CONCLUSION: Prevention of smuggling health goods proves to be a highly complex, challenging, and multi-faceted practice. Therefore, strengthening policy-making, regulatory frameworks, and facilitation functions about smuggling, counterfeiting, and corruption should be promoted in parallel.


Asunto(s)
Investigación Cualitativa , Irán , Humanos , Entrevistas como Asunto , Tráfico de Drogas/prevención & control , Formulación de Políticas , Medicamentos Falsificados , Fraude/prevención & control , Política de Salud
11.
Adv Sci (Weinh) ; 11(30): e2400693, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38867440

RESUMEN

Colloidal carbon dots (CDs) have garnered much attention as metal-free photoluminescent nanomaterials, yet creation of solid-state fluorescent (SSF) materials emitting in the deep red (DR) to near-infrared (NIR) range poses a significant challenge with practical implications. To address this challenge and to engineer photonic functionalities, a micro-resonator architecture is developed using carbonized polymer microspheres (CPMs), evolved from conventional colloidal nanodots. Gram-scale production of CPMs utilizes controlled microscopic phase separation facilitated by natural peptide cross-linking during hydrothermal processing. The resulting microstructure effectively suppresses aggregation-induced quenching (AIQ), enabling strong solid-state light emission. Both experimental and theoretical analysis support a role for extended π-conjugated polycyclic aromatic hydrocarbons (PAHs) trapped within these microstructures, which exhibit a progressive red shift in light absorption/emission toward the NIR range. Moreover, the highly spherical shape of CPMs endows them with innate photonic functionalities in combination with their intrinsic CD-based attributes. Harnessing their excitation wavelength-dependent photoluminescent (PL) property, a single CPM exhibits whispering-gallery modes (WGMs) that are emission-tunable from the DR to the NIR. This type of newly developed microresonator can serve as, for example, unclonable anti-counterfeiting labels. This innovative cross-cutting approach, combining photonics and chemistry, offers robust, bottom-up, built-in photonic functionality with diverse NIR applications.

12.
Sci Rep ; 14(1): 10360, 2024 05 06.
Artículo en Inglés | MEDLINE | ID: mdl-38710733

RESUMEN

An experimental design and response surface methodologies using Plackett-Burman and Box-Behnken designs were applied for selecting and optimizing the most appropriate parameters which significantly affect the separation and quantitative estimation of five skeletal muscle relaxants and four analgesic drugs (baclofen, methocarbamol, dantrolene sodium, orphenadrine citrate, cyclobenzaprine hydrochloride, ketoprofen, etoricoxib, ibuprofen, and mefenamic acid) with a relatively short duration of analysis in a single run. For the separation of the nine drugs, an INERTSIL ODS-V3-5 µm C18 column (250 × 4.6 mm I.D.) was used with the optimum mobile phase conditions (45.15 mM ammonium acetate buffer pH 5.56 adjusted with acetic acid, acetonitrile, and methanol in a ratio of 30.5:29.5:40, v/v/v with a flow rate of 1.5 mL/min) and UV-detection at 220 nm. The optimized method was successfully subjected to the validation steps as described in ICH guidelines for linearity, precision, accuracy, robustness, and sensitivity. The optimized and validated method was effectively applied to determine the content of the studied drugs in their pharmaceutical preparations and to expand its applicability to the counterfeit estimation of etoricoxib in different brands of tablet dosage forms.


Asunto(s)
Analgésicos , Cromatografía Líquida de Alta Presión/métodos , Analgésicos/análisis , Fármacos Neuromusculares/análisis , Reproducibilidad de los Resultados , Cromatografía de Fase Inversa/métodos , Proyectos de Investigación
13.
Neurol Ther ; 13(4): 965-973, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38727766

RESUMEN

Etizolam is a thienodiazepine derivative which produces an anxiolytic effect similar to benzodiazepines such as alprazolam (Xanax). Like classic benzodiazepines, etizolam has a high affinity towards the GABAA receptor, and allosterically potentiates the effects of GABA resulting in neuronal hyperpolarization related to chloride influx. When taken in therapeutic doses, etizolam produces a similar effect to Xanax. Counterfeit Xanax tablets contain variable amounts of etizolam. Tablets with high amounts of etizolam can cause toxicity if ingested, especially when combined with other substances. When toxic symptoms occur in patients, they may include severe sedation, unconsciousness, and depression of the medullary respiratory center. In this regard, there is the potential for death. Additionally, the rise in fake Xanax tablets containing etizolam and other counterfeit medications has been exacerbated by the difference in regulations regarding these substances in different countries as well as the illegal drug trade. Healthcare providers may also play a role through the over- or underprescribing of certain medications. Thus, in order to combat the rise in counterfeit medications such as fake Xanax, international cooperation, regulation, and enforcement of laws pertaining to the manufacture, prescription, and distribution of these substances are needed.

14.
Vet Med (Auckl) ; 15: 91-108, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38595914

RESUMEN

Background: The intentional and illegal misrepresentation of fake medications involves falsely indicating their source. These fraudulent medications can include products that contain either accurate or incorrect ingredients, lack proper labeling, have insufficient quantities of ingredients, and are packaged with counterfeit packaging. This unlawful activity has led to treatment failures, the development of antibiotic resistance, adverse effects, and even deaths. Hence, the objective of this study was to assess the knowledge, practice, and regulatory status of veterinary drug experts in the central Gondar zone of Ethiopia regarding counterfeit veterinary medications. Methods: From January 2023 to July 2023, a self-administered structured questionnaire was utilized to conduct a cross-sectional study in Central Gondar Zone, Ethiopia. The analysis of the data involved the application of descriptive and chi-square tests. Results: The study revealed that the majority of professionals possessed a work experience ranging from 5 to 9 years (23; 56.1%). Additionally, a total of 25 individuals (61.0%) who participated in the research had not undergone any kind of training. It was observed that a significant proportion of participants (82.9%) possessed knowledge about counterfeit veterinary drugs. Only about 63% and 36% of respondents had high knowledge and good practice concerning veterinary counterfeit drugs, respectively. Only 29.3% of participants have reported practices. Furthermore, a poor regulatory level of coordination was detected (85.4%). The study revealed a significant (χ2 =7.6165; p = 0.022) disparity between the respondents' practice levels and training. Respondents' regulatory levels were also significantly associated (p < 0.05) with their sex (χ2 = 13.34; p = 0.001) and work experience (χ2 = 13.64; p = 0.033). The research findings also revealed a noteworthy correlation between practice and regulatory activity (χ2 = 15.0463; p = 0.005). Conclusion: The study outlines the necessity of awareness initiatives, with a focus on the significance of veterinary experts' knowledge, practice, and regulatory efforts in addressing the issue of counterfeit veterinary medications.

16.
Forensic Sci Int ; 357: 111977, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38503039

RESUMEN

Counterfeiting of alcoholic beverages, particularly high-value spirits such as whiskey, presents significant challenges for regulators, manufacturers, and consumers. In this study, we introduce and validate a novel application of headspace extraction (HS) followed by gas chromatography with flame ionization detection (GC-FID) for the quantitative determination of ethanol content in 42 suspected counterfeit brazilian samples of whiskeys. This method, in conjunction with visual inspection of material inconsistencies, offers a combined approach to identify potential cases of fraud. The HS-GC-FID findings revealed that only 19% of the analyzed samples had ethanol content in the limits declared on the label, emphasizing the role of ethanol content as a chemical marker for suspected beverage fraud.

17.
Food Chem ; 447: 139023, 2024 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-38507949

RESUMEN

This study presents a method employing gas chromatography coupled with mass spectrometry and headspace solid-phase microextraction (HS-SPME-GC-MS), supplemented with chemometrics (Soft independent modelling of class analogies - SIMCA), to analyze volatile organic compound (VOCs) profiles in suspect whiskey samples. Furthermore, a sensory analysis of aroma and color was conducted with a panel of 52 non-trained volunteers to evaluate their ability to discriminate and preference for counterfeit whiskeys. The HS-SPME-GC-MS method successfully distinguished 41 seized samples from authentic beverages. Interestingly, sensory analysis revealed that panelists could differentiate between counterfeit and authentic samples with a reference standard but did not consistently show a preference for aroma. In some cases, there was even a preference for the color of counterfeit whiskeys. The findings suggest that sensorial tests alone may not effectively distinguish counterfeit from authentic whiskeys, especially for non-expert consumers, highlighting the need for analytical instrumentation methods in fraud detection.


Asunto(s)
Odorantes , Compuestos Orgánicos Volátiles , Humanos , Odorantes/análisis , Compuestos Orgánicos Volátiles/análisis , Bebidas Alcohólicas/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Espectrometría de Masas , Microextracción en Fase Sólida/métodos
18.
Sci Justice ; 64(2): 202-209, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38431377

RESUMEN

The serial character of document fraud and its connection to organised crime groups who produce, sell and/or use fraudulent documents is a challenge for security and crime fighting. As a response, the added value of forensic intelligence is increasingly recognised. Using a forensic profiling method and a dedicated system deployed in Switzerland, document examiners can detect series (i.e., documents that share a common source) of fraudulent documents conveniently and efficiently. This detection can trigger or orientate investigations, supports crime intelligence efforts, and facilitates cross-jurisdictional cooperation. This study aims to assess the suitability of the forensic profiling system for international purpose and the efficiency of the method to detect cross-border series. The forensic profiling system has been deployed in France in the framework of a cross-border pilot project conducted by the School of Criminal Justice from the University of Lausanne and the French National Police (Division Nationale de Lutte contre la Fraude Documentaire et à l'Identité) over the period July 2019-May 2020. Data from the Swiss and French forensic profiling systems were compared to each other to detect cross-border series. The study sought to create operating conditions as close as possible to the real-life conditions of the profiling systems. The results are extremely positive both quantitatively and qualitatively. They demonstrate the benefit of setting up a systematic exchange of forensic data issued from profiling systems for fraudulent identity documents between France and Switzerland, let alone between any other countries. The results open up a very promising prospect for a sustained operational implementation by the police services of both countries and the extension of the exchanges internationally.


Asunto(s)
Crimen , Registros , Humanos , Suiza , Proyectos Piloto , Francia
19.
Macromol Rapid Commun ; 45(9): e2300652, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38407457

RESUMEN

Pyrrole-based polymers (PBPs), a type of fascinating functional polymers, play a crucial role in materials science. However, efficient synthetic strategies of PBPs with diverse structures are mainly focused on conjugated polypyrroles and still remain challenging. Herein, an atom and step economy protocol is described to access various 2,4-disubstituted PBPs by in situ formation of pyrrole core structure via copper-catalyzed [3+2] polycycloaddition of dialkynones and diisocyanoacetates. A series of PBPs is prepared with high molecular weight (Mw up to 18 200 Da) and moderate to good yield (up to 87%), which possesses a fluorescent emission located in the green to yellow light region. Blending the PBPs with polyvinyl alcohol, the stretchable composite films exhibit a significant strengthening of the mechanical properties (tensile stress up to 59 MPa, elongation at break >400%) and an unprecedented stress-responsive luminescence enhancement that over fourfold fluorescent emission intensity is maintained upon stretching up to 100%. On the basis of computational studies, the unique photophysical and mechanical properties are attributed to the substitution of carbonyl chromophores on the pyrrole unit.


Asunto(s)
Cobre , Polímeros , Pirroles , Pirroles/química , Cobre/química , Catálisis , Polímeros/química , Polímeros/síntesis química , Estructura Molecular , Reacción de Cicloadición
20.
Spectrochim Acta A Mol Biomol Spectrosc ; 312: 124068, 2024 May 05.
Artículo en Inglés | MEDLINE | ID: mdl-38417234

RESUMEN

The health of consumers can be impacted by the additives placed into the liquor. To address the issues of poor accuracy, low reliability, and complex operational procedures in identifying adulteration in existing liquor, an improved convex non-negative matrix factorization (ICNAFS) with an adaptive graph constraint for unsupervised feature extraction is proposed in this paper, with the goal of achieving rapid identification of adulteration in liquor by Raman spectroscopy through dimensionality reduction. For the sake to streamline the calculation process for effective feature extraction and increase the accuracy of the analyzed model, the proposed ICNAFS method incorporates two fundamental models, such as ridge regression and convex non-negative matrix factorization (NMF). In particular, dimensionality reduction of the original spectrum is initially conducted using Principal Component Analysis (PCA), Sequential Projection Algorithm (SPA), Convex Non-Negative Matrix Factorization with an Adaptive Graph Constraint (CNAFS), and ICNAFS respectively. k-means is subsequently employed to merge the four models for clustering analysis. The results suggest that the accuracy of the presented ICNAFS-assisted k-means model is higher than the other techniques, with a clustering accuracy of 98.67%, exhibiting a 4% improvement over the existing CNAFS, through examination of 150 sets of tainted liquor data from five categories of samples. This demonstrates the potency of the proposed ICNAFS-assisted k-means clustering model in conjunction with Raman spectroscopy as a method for detecting tainted liquor.

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