Chemical Experiments Research Articles

Comprehensive undergraduate experiment: determination of phenylurea herbicide in tea by magnetic solid-phase extraction-high performance liquid chromatography

Against the backdrop of the Ministry of Education's promotion of new agricultural science construction and interdisciplinary integration, a comprehensive chemistry experiment to enhance the practical skills of students in preparing biomass functional materials and detecting pesticide residues was designed. Natural loofah was utilized as a precursor in synthesizing nitrogen-doped magnetic porous carbon materials, which were then applied in a magnetic solid-phase extraction (MSPE) technique. Subsequently, high performance liquid chromatography (HPLC) was employed to analyze and detect the phenylurea herbicide monuron in tea. The experimental process included material synthesis, characterization, optimization of the MSPE conditions, adsorption performance studies, and HPLC, reflecting its scientific, systematic nature and providing a comprehensive learning platform for students. It not only deepens student understanding of the relationship between material characterization and application, but also improves their experimental design and problem-solving capacities. Moreover, by integrating cutting-edge science, ideological and political education, and experimental training, it not only stimulates student interest in scientific research and cultivates innovative thinking and practical skills, but also strengthens their feelings of social responsibility and historical mission. This approach realizes the comprehensive educational goals of experimental training and lays the foundation for nurturing high-quality talent with a global perspective and sense of social responsibility.

Investigating the vertical extent of the 2023 summer Canadian wildfire impacts with satellite observations

Abstract. Pyrocumulonimbus clouds (pyroCbs) generated by intense wildfires can serve as a direct pathway for the injection of aerosols and gaseous pollutants into the lower stratosphere, resulting in significant chemical, radiative, and dynamical changes. Canada experienced an extremely severe wildfire season in 2023, with a total area burned that substantially exceeded those of previous events known to have impacted the stratosphere (such as the 2020 Australian fires). This season also had record-high pyroCb activity, which raises the question of whether the 2023 Canadian event resulted in significant stratospheric perturbations. Here, we investigate this anomalous wildfire season using retrievals from multiple satellite instruments, ACE-FTS (Atmospheric Chemistry Experiment – Fourier transform spectrometer), OMPS LP (Ozone Mapping and Profiler Suite Limb Profiler), and MLS (Microwave Limb Sounder), to determine the vertical extents of the wildfire smoke along with chemical signatures of biomass burning. These data show that smoke primarily reached the upper troposphere, and only a nominal amount managed to penetrate the tropopause. Only a few ACE-FTS occultations captured elevated abundances of biomass-burning products in the lowermost stratosphere. OMPS LP aerosol measurements also indicate that any smoke that made it past the tropopause did not last long enough or reach high enough to significantly perturb stratospheric composition. While this work focuses on Canadian wildfires given the extensive burned area, pyroCbs at other longitudes (e.g., Siberia) are also captured in the compositional analysis. These results highlight that despite the formation of many pyroCbs in major wildfires, those capable of penetrating the tropopause are extremely rare; this in turn means that even a massive area burned is not necessarily an indicator of stratospheric effects.

A virtual 3D Chemistry Escape Room for Exam Preparations

Chemistry can be incredibly captivating. However, learning the theory can often be challenging and less appealing for students. Providing them with hands-on methods in their learning process is beneficial and also helps to lower the barrier for understanding theory. In a gamified approach, the "ChemScape" virtual 3D chemistry escape room, designed as a realistic laboratory with various equipment and hidden chemical tasks, can help solidify chemical knowledge and prepare students for chemistry exams. In 2023, as part of an e-learning project, the foundation of such a chemistry escape room was established, and several chemical questions were incorporated as escape room tasks. The objective is to discover hidden questions within the laboratory, utilize different instruments (such as scales), conduct virtual chemistry experiments, and solve various chemistry questions using theoretical knowledge (such as nomenclature and understanding of pH) in a game-based setting (utilizing multiple-choice, drag and drop, connecting cables, solving color codes, etc.). Typically, a code (comprising numbers, letters, signs, etc.) needs to be obtained for progression. To solve the chemistry tasks, approximately 10 different door-openers have been developed. Initial user tests have been conducted, and adjustments were made based on the feedback received, which was satisfactory and positive. In 2024, the "ChemScape" escape room will evolve from a game with a fixed set of tasks to a dynamic escape room game with a dynamic database that allows for the creation of new questions at the same stations, significantly expanding learning opportunities. A virtual chemistry laboratory rat provides hints if a participant gets stuck and requires assistance. Furthermore, "ChemScape" will be trialed in chemistry lectures and potentially utilized as an additional attraction at events held at the University of Applied Sciences.

Sulfur dioxide sources in the stratosphere

Version 5.2 SO2 data from the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) in low Earth orbit are used to determine global altitude-latitude abundance distributions. This new data set has SO2 volume mixing ratios (VMRs) from 11.5 to 39.5 km in altitude from February 2004 to July 2023. The average background SO2 abundance is plotted along with the abundance for four different seasons. These distributions show that there is a stratospheric source of SO2 that comes from the decline in sulfate aerosol abundance with increasing altitude. The visible and near-infrared photolysis of sulfuric acid (H2SO4) is the primary source of SO2 in the middle stratosphere. There is also a source of SO2 in the upper stratosphere and mesosphere. The Brewer-Dobson circulation enhances SO2 at higher altitudes, particularly by descent near the winter pole. The elevated abundance of SO2 near the poles originates from meteoric sources as well as UV photolysis of H2SO4 in the mesosphere. Large volcanic eruptions release sulfur dioxide (SO2) into the lower stratosphere, where it persists for several months.

The first satellite measurements of HFC-125 by the ACE-FTS: Long-term trends and distribution in the Earth’s upper troposphere and lower stratosphere

HFC-125 (CF3CHF2, pentafluoroethane) volume mixing ratios (VMRs) have been determined for the first time using infrared absorption spectra from the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) from 2004 to 2024. These VMRs provide global altitude-latitude VMR distributions. A VMR time series for HFC-125 has also been calculated and compared to values from in situ discrete flask measurements conducted by the National Oceanic and Atmospheric Administration Earth System Research Laboratory. The abundance of HFC-125 is currently experiencing exponential growth. ACE data shows a growth rate of 3.47 ± 0.05 ppt/year in the past six years.

Видео експериментът в обучението модел за приложението му при изучаване на химия и опазване на околната среда

In this paper, the focus is on the video experiment in learning. Its application in the teaching of Chemistry and Environmental Protection is justified. A model for the planning and implementation of video experiments in education is developed and presented through its main components in their interrelation and conditioning. The guiding idea on which the proposed model is based is the development of interest in the study of chemical science and the creation of conditions for the development of key competencies in science. The model is concretized and tested in the practice of organic chemistry education. On the basis of the proposed model 11 educational videos have been created, the applicability of which has been established by expert evaluation. For the implementation of the expertise, requirements for the virtual chemistry experiments have been defined, which can be used for both formative (in-process) and final assessment.

In Situ Growth of COFs within Cork for Oil–Water Separation: A Comprehensive Chemistry Experiment for Undergraduates

In Situ Growth of COFs within Cork for Oil–Water Separation: A Comprehensive Chemistry Experiment for Undergraduates

A Trend Analysis of Project-based Learning in Chemistry Experiment: A Bibliometric Analysis

Project-based learning is a global trend, widely adopted across countries. Project-based learning has developed diversely by emphasizing interdisciplinary, cross-domain, and regional collaboration. To provide in-depth resources for researchers and educators on project-based learning in chemistry experiments, this study aims to make a bibliometric analysis on the topic of project-based learning globally using publication characteristics analysis. The database used in this study used Scopus and obtained 5900 articles from 2018-2023. Bibliometric analysis was analyzed using VOSviewer and Microsoft Excel. The results of the bibliometric analysis show that Boone, C.D. is the author with the highest number of citations on the research topic, Project-based learning in a chemistry experiment. The United States is the most productive country in researching this topic, with 1351 articles. The most influential journal with the highest number of articles is the Journal of Physics Conference Series, with 243 articles. The major contextualized learning literatures in this study tend to fall into broad groups such as Project-based Learning, Education, and STEM Education. These findings suggest the need for multidisciplinary and cross-disciplinary studies on project-based learning research on chemistry learning and advocate for the inclusion of project-based learning research in education from a broader geographical context.

An Automated Electrochemical Flow Platform to Accelerate Library Synthesis and Reaction Optimization

Automated batch and flow reactors are well‐established for high throughput experimentation in both thermal chemistry and photochemistry. However, the development of automated electrochemical platforms is hindered by cell miniaturization challenges in batch and difficulties in designing effective single‐pass flow systems. In order to address these issues, we have designed and implemented a new, slug‐based automated electrochemical flow platform. This platform was successfully demonstrated for electrochemical C‐N cross‐couplings of E3 ligase binders with diverse amines (44 examples), which were subsequently transferred to a continuous‐flow mode for confirmation and isolation, showing its applicability for medicinal chemistry purposes. To further validate the versatility of the platform, Design of Experiments (DoE) optimization was performed for an unsuccessful library target. This optimization process, fully automated by the platform, resulted in a remarkable 6‐fold increase in reaction yield.

An Automated Electrochemical Flow Platform to Accelerate Library Synthesis and Reaction Optimization.

Automated batch and flow reactors are well-established for high throughput experimentation in both thermal chemistry and photochemistry. However, the development of automated electrochemical platforms is hindered by cell miniaturization challenges in batch and difficulties in designing effective single-pass flow systems. In order to address these issues, we have designed and implemented a new, slug-based automated electrochemical flow platform. This platform was successfully demonstrated for electrochemical C-N cross-couplings of E3 ligase binders with diverse amines (44 examples), which were subsequently transferred to a continuous-flow mode for confirmation and isolation, showing its applicability for medicinal chemistry purposes. To further validate the versatility of the platform, Design of Experiments (DoE) optimization was performed for an unsuccessful library target. This optimization process, fully automated by the platform, resulted in a remarkable 6-fold increase in reaction yield.

TIMM9 as a prognostic biomarker in multiple cancers and its associated biological processes

TIMM9 has been identified as a mediator of essential functions in mitochondria, but its association with pan-cancer is poorly understood. We herein employed bioinformatics, computational chemistry techniques and experiments to investigate the role of TIMM9 in pan-cancer. Our analysis revealed that overexpression of TIMM9 was significantly associated with tumorigenesis, pathological stage progression, and metastasis. Missense mutations (particularly the S49L variant), copy number variations (CNV) and methylation alterations in TIMM9 were found to be associated with poor cancer prognosis. Moreover, TIMM9 was positively related with cell cycle progression, mitochondrial and ribosomal function, oxidative phosphorylation, TCA cycle activity, innate and adaptive immunity. Additionally, we discovered that TIMM9 could be regulated by cancer-associated signaling pathways, such as the mTOR pathway. Using molecular simulations, we identified ITFG1 as the protein that has the strongest physical association with TIMM9, which show a promising structural complement.

Atmospheric pressure atomic layer deposition for in-channel surface modification of PDMS microfluidic chips

Polydimethylsiloxane (PDMS) is one of the materials of choice for the fabrication of microfluidic chips. However, its broad application is constrained by its incompatibility with common organic solvents and the absence of surface anchoring groups for surface functionalization. Current solutions involving bulk-, ex-situ surface-, and in-situ liquid phase modifications are limited and practically demanding. In this work, we present a simple, novel strategy to deposit a metal oxide nano-layer on the inside of bonded PDMS microfluidic channels using atmospheric pressure atomic layer deposition (AP-ALD). Using three important classes of microfluidic experiments, i.e., (i) the production of micron-sized particles, (ii) the cultivation of biological cells, and (iii) the photocatalytic degradation in continuous flow chemistry, we demonstrate that the metal oxide nano-layer offers a higher resistance against organic solvent swelling, higher hydrophilicity, and a higher degree of further functionalization of the wall. We demonstrate the versatility of the approach by not only depositing SiOx nano-layers, but also TiOx nano-layers, which in the case of the flow chemistry experiment were further functionalized with gold nanoparticles through the use of AP-ALD. This study demonstrates AP-ALD as a tool to broaden the applicability of PDMS devices.

Research on Teaching Reform of Chemistry Experimental Course under New Engineering Background

With the proposal of new engineering education concept, new challenges are posed to the teaching reform of chemical experiment course. This study aims to explore the teaching reform path of chemistry experiment course under the new engineering background, so as to improve the students' practical ability and innovation ability. As an important part of engineering education, the teaching objectives of chemistry experiment should be consistent with the new engineering education concept, and pay attention to cultivating students' ability to solve practical problems and teamwork spirit. At present, there are some problems in chemistry experiment teaching, such as outdated curriculum system, too theoretical experiment content, lack of combination with engineering practice, and low participation of students. These problems restrict the improvement of teaching quality, and can not meet the needs of new engineering education for talent training. Therefore, the primary task of the reform is to update the experimental curriculum system and integrate more experimental projects with engineering background and cutting-edge technology, in order to improve the practicality and challenge of the experiment. In terms of reform strategies, it is suggested to implement the "student-centered" teaching mode, and encourage students to take the initiative to explore and innovate through project-driven and problem-oriented teaching methods. At the same time, strengthen the integration of experimental teaching and theoretical teaching, so that students can deepen the understanding of theoretical knowledge in the experiment, and use theoretical knowledge to solve practical problems. In addition, the information level of experimental teaching should be improved, and virtual simulation and other technologies should be used to expand the space-time dimension of experimental teaching and improve the teaching effect. The change of the role of teachers is also the key. Teachers should change from the teacher of knowledge to the guide and collaborator of students' learning. By building an open and interactive classroom environment, stimulate students' interest in learning and innovative thinking. At the same time, the establishment of a diversified evaluation system, in addition to the investigation of students' experimental skills, but also should pay attention to the evaluation of their innovative thinking, teamwork and solving practical problems. To sum up, the teaching reform of chemistry experimental curriculum under the background of new engineering should focus on the update of curriculum content, the transformation of teaching mode, the integration of teaching resources and the reform of evaluation system. Through the implementation of these strategies, it aims to build an experimental teaching system that can not only meet the needs of new engineering education, but also cultivate high-quality chemical engineering talents. Such reform is of great significance to enhance the competitiveness of chemical engineering education in China.

Correction to “Shrimp-Shell-Derived Carbon Dots for Quantitative Detection by Fluorometry and Colorimetry: A New Analytic Chemistry Experiment for University Education”

Correction to “Shrimp-Shell-Derived Carbon Dots for Quantitative Detection by Fluorometry and Colorimetry: A New Analytic Chemistry Experiment for University Education”

(Invited) Machine Learning in Chemistry: Reactive Force Fields for Carbon Structure Formation

Machine learning (ML) became a premier tool for modeling chemical processes and materials properties. ML interatomic potentials have become an efficient alternative to computationally expensive quantum chemistry simulations. In the case of reactive chemistry designing high-quality training data sets is crucial to overall model accuracy. To address this challenge, we develop a general reactive ML interatomic potential through unbiased active learning with an atomic configuration sampler inspired by nanoreactor molecular dynamics. The resulting model is then applied to study five distinct condensed-phase reactive chemistry systems: carbon solid-phase nucleation, graphene ring formation from acetylene, biofuel additives, combustion of methane and the spontaneous formation of glycine from early-earth small molecules. In all cases, the results closely match experiment and/or previous studies using traditional model chemistry methods. Importantly, the model does not need to be refit for each application, enabling high throughput in silico reactive chemistry experimentation.

A microbiome-biochar composite synergistically eliminates the environmental risks of antibiotic mixtures and their toxic byproducts

This study developed a continuous reactor system employing a hybrid hydrogel composite synthesized using a complex sludge microbiome and an adsorbent (HSA). This HSA-based system effectively eliminated the environmental risks associated with a mixture of the antibiotics ciprofloxacin and sulfamethoxazole, which exhibited higher toxicity in combination than individually at environmentally relevant levels. Analytical chemistry experiments revealed the in-situ generation of various byproducts (BPs) within the bioreactor system, with two of these BPs recording toxicity levels that surpassed those of their parent compound. The HSA approach successfully prevented the functional microbiome from being washed out of the reactor, while HSA efficiently removed antibiotic residues in their original and BP forms through synergistic adsorptive and biotransformation mechanisms, ultimately reducing the overall ecotoxicity. The use of HSA thus demonstrates promise not only as a mean to reduce the threat posed by toxic antibiotic residues to aquatic ecosystems but also as a practical solution to operational challenges, such as biomass loss/washout, that are frequently encountered in various environmental bioprocesses.

Reactive Nitrogen Partitioning Enhances the Contribution of Canadian Wildfire Plumes to US Ozone Air Quality

AbstractQuantifying the variable impacts of wildfire smoke on ozone air quality is challenging. Here we use airborne measurements from the 2018 Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN) to parameterize emissions of reactive nitrogen (NOy) from wildfires into peroxyacetyl nitrate (PAN; 37%), NO3− (27%), and NO (36%) in a global chemistry‐climate model with 13 km spatial resolution over the contiguous US. The NOy partitioning, compared with emitting all NOy as NO, reduces model ozone bias in near‐fire smoke plumes sampled by the aircraft and enhances ozone downwind by 5–10 ppbv when Canadian smoke plumes travel to Washington, Utah, Colorado, and Texas. Using multi‐platform observations, we identify the smoke‐influenced days with daily maximum 8‐hr average (MDA8) ozone of 70–88 ppbv in Kennewick, Salt Lake City, Denver and Dallas. On these days, wildfire smoke enhanced MDA8 ozone by 5–25 ppbv, through ozone produced remotely during plume transport and locally via interactions of smoke plume with urban emissions.

Evolution of the different types of catalytic sites in aminosilica materials during recycle experiments in aldol chemistry

Aminosilica materials are promising for many applications, including as a catalyst for aldol chemistry. Whereas aminosilica catalysts are known to deactivate overtime, it is unclear how recent revelations about the different types of catalytic sites impact the understanding of the deactivation behavior. In this work, we investigate how the aminosilica catalyst activity decreases and affects the fraction and the type of active sites. After a single catalytic cycle, the catalyst activity decreases, but the fraction of active sites remains constant. The decrease in catalytic activity is consistent with the conversion of medium and high activity sites transfer to low activity sites that lack cooperative interactions. Additional catalytic cycles decrease the fraction of active sites but do not result in aminosilane leaching. The sites are inactive because of accumulation of organic content. Interestingly, the organic can be removed through washing with a dilute sodium carbonate solution. The washed material fully recovers to the catalytic activity of the fresh material. Overall, the catalytic sites evolve after each cycle, but this trend can be reversed, enabling aminosilica materials to be used as sustainable catalysts for aldol chemistry.

Temperature retrieval of near space with the combined use of O2(a1Δg) and O2(b1∑+ g) dayglow emissions under self-absorption effect correction

Atmospheric temperature information in the near space is of great academic significance and engineering value to support the development and utilization of the near space. Based on the theory of O2 molecular dayglow spectroscopy and the mechanism of atmospheric radiative transfer, a method is proposed for the joint retrieval of temperature profiles in the near space using O2(a1Δg) and O2(b1∑+g) bands dayglow spectroscopy signal with the self-absorption effect. First, the temperature dependence of O2(a1Δg) and O2(b1∑+g) bands dayglow is investigated, and the influence of the self-absorption effect on the radiative transfer characteristics is analyzed in the limb-view mode. Then, with the use of the onion peeling algorithm, the dayglow emission spectra signals of the O2(a1Δg) and O2(b1∑+g) bands measured by the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) in the limb-viewing mode were processed, and combined with optimization algorithms, the temperature profiles from 35 km to 120 km is successfully retrieved. Finally, the accuracy and reliability of the self-absorption effect correction as well as the joint temperature retrieval were verified by comparing with temperature product data from remote sensing satellites such as Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), Atmospheric Chemistry Experiment Fourier-Transform Spectrometer (ACE-FTS), and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). The error analysis shows that the temperature retrieval error after correction for the self-absorption effect is about 3 K minimum and 20 K maximum.

A Modular Variable Temperature FT-IMS Instrument Optimized for Gas-Phase Ion Chemistry Applications.

The latest iteration of modular, open-source rolled ion mobility spectrometers was characterized and tailored for heated ion chemistry experiments. Because the nature of ion-neutral interactions is innately linked to the temperature of the drift cell, heated IMS experiments explicitly probe the fundamental characteristics of these collisions. While classic mobility experiments examine ions through inert buffer gases, doping the drift cell with reactive vapor enables desolvated chemical reactions to be studied. By using materials with minimal outgassing and ensuring the isolation of the drift tube from the surrounding ambient conditions, an open-source drift cell outfitted with heating components enables investigations of chemical reactions as a function of temperature. We show here that elevated temperatures facilitate an increase in deuterium incorporation and allow for hydrogen/deuterium exchanges otherwise unattainable under ambient conditions. While the initial fast exchanges get faster as temperature is increased, the slow rate which rises from the kinetic nonlinearity though to be attributed to ion-neutral clustering, remains constant with no change in mobility shifts. Additionally, we show the analytical merit of multiplexing mobility data by comparing the performance of traditional signal-averaging and FT-IMS modes.