Chemical Concepts Research Articles

Retracted:An integrated protocol based on workflows of imaged capillary isoelectric focusing (icIEF) for in-depth protein heterogenous characterization: High-efficient fractionation and online mass spectrometry detection

Herein we describe an integrated protocol to study the charge heterogeneity of therapeutic proteins. The protocol integrating two workflows, based on imaged capillary isoelectric focusing (icIEF) with fractionation and mass spectrometry (MS) online detection on the same platform, is validated, and can be used for protein charge variant characterization at intact MS and in-depth peptide mapping of collected fractions by high performance liquid chromatography (HPLC). The developed protocol was evaluated based on systematic methodology validation, which is demonstrated to be a robust platform that suits for the heterogeneity characterization of diverse therapeutic proteins with Standard Operating Procedures (SOP), outstanding reproducibility and excellent sensitivity. Especially, the constructed protocol can perform both functions of icIEF fractionation and MS online detection in a unique icIEF platform with high throughput, easy method development and less reagent consumption as comparing to traditional technologies, which “Green Chemistry Concept” helps biopharma industry address urgent challenges during the whole process of discovery, quality control and manufacture release.

Low-lying LUMO Boosts Conductance in Antiaromatic Dibenzopentalene Versus Aromatic Analogues.

Antiaromaticity is a fundamental concept in chemistry, but the study of molecular wires incorporating antiaromatic units is limited. Despite initial predictions, very few studies show that antiaromaticity has a beneficial effect on electron transport. Dibenzo[a,e]pentalene (DBP) is a stable structure that displays appreciable antiaromaticity within the five-membered rings of the pentalene core. We have investigated derivatives of DBP furnished with pyridyl (Py) and F4-pyridyl (PyF4) anchor groups, and compared the conductance with purely aromatic phenyl and anthracene analogues. We find that the low-bias conductance of DBP-Py is approximately 60 % larger than that of the anthracene analogue Anth-Py and 250 % larger compared to the phenyl derivative Ph-Py. This is due to a better alignment of the LUMO with the gold Fermi level, which we confirm by conductance-voltage spectroscopy where the conductance of DBP-Py shows the greatest voltage-dependence. The F4-pyridyl compounds, which have lower LUMO energies compared to the pyridyl analogues, did not, however, form detectable molecular junctions. The strongly electron-withdrawing fluorine atoms reduce the donor capability of the nitrogen lone-pair to the point where stable N-Au bonds no longer form.

Project Based Learning (PjBL) in Chemistry Learning: Systematic Literature and Bibliometric Review 2015 - 2022

Education is important to form an intelligent and competitive generation. Project Based Learning (PjBL) offers relevant and interactive learning, recognized by Grant (2002) as a student-centered model. PjBL creates a constructivist environment, developing content understanding and skills, such as communication, time management, research and critical thinking. This research focuses on the application of PjBL in chemistry learning, aiming to find out the results of previous research. This research uses Systematic Literature Review (SLR) and bibliometric review as methods. SLR is considered a systematic and transparent method of collecting, synthesizing and assessing study findings on a topic. The process includes planning (research identification), implementation (literature search and selection), and reporting (synthesis of findings). The research question (RQ) focuses on the application of Project Based Learning (PjBL) in chemistry learning. Twenty journals were selected, mostly from Scopus, with criteria ranging from 2015-2020. The analysis showed that 13 journals met the criteria, and a bibliometric review was then carried out on these journals. The research results show that PjBL focuses on skill development, learning innovation, and the impact on student understanding and participation. The research implications highlight the importance of the PjBL model to improve the learning process and better learning tools. The results revealed a wide variety of methods and samples. Six studies focused on the influence of PjBL, critical thinking abilities, psychomotor skills, problem solving, creativity, cognitive achievement, and teamwork. This framework generally involves students' innovative learning and laboratory experiments. Chemistry concepts include analytical, physical, environmental, basic, and organic chemistry. Data collection and analysis tools serve as benchmarks for future research and implications.

Pengembangan Video Praktikum Sederhana Materi Redoks Sebagai Praktikum Alternatif Selama Pandemi COVID-19

Due to COVID-19, media is needed so that students can continue to carry out practical activities at home to improve their understanding of chemical concepts. This study aimed to develop and determine the quality of a simple practicum video on redox material. This research is development research (R&D) with a 4D model (Define, Design, Development, and Disseminate), but this research is only up to the development stage. This simple video practicum on redox material contains the redox process on nail corrosion, the redox process on betadine with vitamin C, and the redox process on Onions with potassium permanganates. The product is assessed by one material expert, one media expert, four reviewers, and ten class X students respond. The results of the product quality assessment by material experts, media experts, and reviewers (senior high school chemistry teachers) get a percentage of 97.14%, 90%, and 91.81%, with a very good category. Then, the results of student responses obtained a percentage of 95% with a very good category. Based on this assessment, it can be concluded that simple practicum videos on redox material can be used as an alternative source of practicum during the COVID-19 era.

Development Of A Chemo-Entrepreneurship Oriented Electronic Module (E-Module) On The Concept Of Buffer Solutions

Innovation in technology-based teaching materials is one of the innovations brought by technological advances in the 21st century in the field of education, one of which is module innovation in electronic form (e-module). However, millennial students currently don't really like learning science, one of which is chemistry because they think it's boring. This can be overcome by learning with a contextual approach, one of which is chemo-entrepreneurship in the form of electronic modules in buffer solution material. Through e-modules, students obtain information about chemical concepts in the processing of materials into chemical-based entrepreneurial products. The aim of this development research is to create a chemo-entrepreneurship oriented electronic module (e-module) based on the buffer solution concept. The ADDIE model which includes the stages of analysis, design, development, implementation and evaluation was used to plan this research. After going through validation by five material experts and media experts, this e-module was declared valid because the V value exceeded 0.80 in the Aiken's test. A total of 19 students of XI MIPA 4 SMA Negeri 8 Serang City were used for limited e-module testing and obtained a percentage of 92% in the very good category. Keywords: Electronic module (e-module), chemo-entrepreneurship, buffer solution, ADDIE

High-accuracy quantitative model for phosphate anions in solution based on absorption spectroscopy and machine learning algorithms

The eutrophication pollution caused by excessive phosphorus seriously affects production and daily life of the people. Accurate and rapid detection of phosphate is crucial for water quality management and cleaner production. Currently, most analytical methods for phosphates involve the addition of multiple chemical reagents and are incapable of simultaneous quantification of total phosphorus (TP) and phosphate anions. The environmental friendliness and analytical performance of the methods need to be improved. Here, we established a green and high-accuracy quantitative model based on absorption spectroscopy and machine learning algorithms, which achieved the analysis of TP, H2PO4− and HPO42−. Based on the pH and absorption spectra of phosphate anions, classification and regression tree (CART), random forest (RF), and extreme gradient boosting (XGBoost) algorithms were used to train the original absorption spectra data, first-order derivative spectra data, and multiple feature parameter data of phosphate solutions with pH 4.7–10.0. By comparing the R2, root mean square error (RMSE) and mean absolute error (MAE) evaluation indicators, it was found that the phosphate anions quantitative model established using the CART based on the feature parameters of 187 nm performed the best, R2 > 0.9999, RMSE <3.4 × 10−6, MAE <8.1 × 10−7. The quantitative ranges of TP, H2PO4−, and HPO42− were 3.98 × 10−4—9.33 × 10−4 mol/L, 5.98 × 10−6—4.20 × 10−4 mol/L and 1.53 × 10−6—7.43 × 10−4 mol/L, respectively. Moreover, the quantitative model was optimized based on the spectral characteristics of 14 interfering ions, to improve the model analytical performance for unknown samples. The quantitative model developed in the study achieves accurate analysis of TP, H2PO4− and HPO42−, which is in line with green chemistry concept, and has the potential for prediction and early warning of water environment quality.

Evaluating the alignment between chemistry curriculum and high-stakes tests through the lens of chemistry core competencies in China

ABSTRACT The study investigates the alignment between the Chemistry Curriculum Standards of Senior High School (Curriculum Standards) and 10 sets of 2023 standards-based high-stakes tests in mainland China through the lens of Chemistry Core Competencies (CCCs). Following Porter’s alignment model, a two-dimensional matrix composed of components of CCCs and proficiency levels of CCCs was developed to represent Curriculum Standards and tests, based on which to compute overall alignment indices and the degree of match for each dimension. The results indicate that all tests value CCCs, but the vast majority have statistically insignificant alignment with Curriculum Standards. This inconsistency is mainly due to the tests’ more emphasis on higher-order thinking skills, which has resulted in an overall shift towards higher proficiency of CCCs from Curriculum Standards to tests. Compared to Curriculum Standards, the tests measure scientific thinking more than chemical concepts, and the ratio of scientific inquiry and practice is most consistent with Curriculum Standards, but minimally assesses scientific attitudes and responsibility. The findings present direct evidence for improving the quality of assessment in the future. The proposal of the alignment analytical framework offers researchers in other countries the possibility of localised exploration.

Development of Learning Videos on Petroleum Materials Using Dora Toon Web Apps for Class XI High School Students

Many students have difficulty understanding chemistry concepts due to limited learning resources such as textbooks and traditional lectures. This research proposes making videos using Dora Toon, an audiovisual web platform specifically for petroleum materials. This project aims to assess video quality through evaluation by research subjects (material experts, media, chemistry educators, and 10 class XI high school students). With a research and development approach, the model used is 4D (define, design, development, disseminate) with a focus on the disseminate stage. The definition stage includes analysis of the front-end, students, concepts, tasks, and learning objectives. The design stages include selecting media format, collecting references, creating initial designs, and making instruments. The development stage includes video production, validation tests on research subjects. Sampling used purposive sampling technique, data collection used a validation questionnaire, and analyzed descriptively in percentages. At the disseminate stage, the product can be distributed to the wider community. However, this stage was not carried out due to time constraints. This results in HD resolution that is easy to use. It produces HD (1280x720p) resolution MP4 videos that are easy to use and contain petroleum ingredients. The evaluation results were very positive. The material expert gave a score of 95% (very good), the media expert gave a score of 95% (very good), the chemistry teacher gave a score of 86.06% (very good), and the students answered positively 100%. These findings indicate that animated videos can be an alternative learning tool for teaching petroleum chemistry in the classroom

Learning with NanoKid: line-angle formula, chemical formula, molecular weight, and elemental analysis

Abstract The conversion from line-angle formula to chemical formula often poses a challenge for first-year nonchemistry majors. To address this, the authors developed an engaging exercise lecture that encompasses the conversion process and related chemistry concepts, including molecular weight and elemental analysis. Initially, the instructor reviews basic chemistry concepts with the students. Subsequently, students construct a NanoKid structure model using transistors and red LEDs connected by plastic tubes, representing carbon and oxygen atoms, respectively. By referencing their models, students identify the chemical formula of NanoKid, calculate its molecular weight, and perform elemental analysis under the guidance of the instructor. Additionally, they estimate the scale of the NanoKid model relative to the actual NanoKid molecule. The exercise promotes peer review among students and is completed within approximately 45 min. A post-lecture questionnaire revealed that the exercise was well-received by the students.

Conflicting Aromaticity in Trirhodium(I) Rosarin.

Aromaticity is one of the most important and widely used concepts in chemistry. Among the various experimentally discovered and theoretically predicted compounds that possess different types of aromaticity, conflicting aromaticity, where aromatic and antiaromatic electron delocalization is present in one molecule simultaneously, remains one of the most controversial and elusive concepts, although theoretically predicted 15 years ago. In this work, we synthesized a novel conflicting aromatic trirhodium complex that contains a σ-aromatic metal fragment surrounded by the π-antiaromatic organic ligand and characterized it by nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, and X-ray single crystal structure analysis. Experimental characterization and quantum chemical calculations confirm the unique conflicting aromaticity of the synthesized trirhodium molecule. Thus, this novel conflicting aromatic molecule expands the family of aromatic compounds. This discovery will enable researchers to develop and understand the phenomena of conflicting aromaticity in chemistry.

Derivation of Morse potential

The Morse potential is widely used in chemistry, physics, and material science to describe interatomic interactions. We show that the Morse potential can be derived from a simple screened charge model accounting for the shielding of the nuclear charge by electron density. In this model, the parameter governing the width of the potential is related to the average shielding strength and the exponents of the atomic orbitals used in electronic structure calculations. The parameter representing the bond dissociation energy of a diatomic molecule is derived by combining the quantum mechanical covalent and classical electrostatic interactions. Moreover, the revealed connection between the parameters of the Morse potential and Pauling’s bond order and electronegativity provides insight into the relation between the classical and quantum mechanical descriptions of chemical bonds. This derivation of the Morse potential from the atomic quantities is expected to contribute to the development of the new basis sets incorporating Slater-type orbitals for electronic structure calculations and the transferable reactive force fields for molecular dynamics simulations. Furthermore, this interpretation of the Morse potential helps to understand the relationships between widely used chemical concepts, including effective atomic charge, bond dissociation energy, electronegativity, and bond order.

A Review on Piezoelectric-mediated Mechanoredox Reactions by Ball Milling in Organic Synthesis

Abstract: Recently, the concept of mechanoredox chemistry has been proposed and welldeveloped in organic synthesis. Mechanoredox chemistry is conceptually similar to a photocatalyst reaction system, where piezoelectric materials are introduced to the reaction system in a manner analogous to photoredox catalysis. These reactions feature the ability to generate high-value radicals that do not require harsh reaction conditions of anhydrous and anaerobic conditions, an expensive photocatalyst, and the use of solvents, which renders these transformations highly industrially applicable. In addition, mechanoredox chemistry is also an emerging interdisciplinary research field that combines material chemistry with synthetic chemistry to create more useful reactions. This review provides a comprehensive summary of progress to date in the specific transformation and related mechanisms of piezoelectric- mediated mechanoredox reactions by ball milling in organic synthesis.

Feasibility of Four-Tier Multiple Choice Diagnostic Test for Identification Conception on Chemical Equilibrium Concept

The purpose of this study was to obtain the feasibility of a four-tier multiple choice (4TMC) diagnostic test instrument for the identification of conceptions on chemical equilibrium material in terms of validity, practicality, and effectiveness criteria. This type of research is ADDIE development research with the Analyze, Design, Development, and Evaluation stages. Validity is obtained from a validation sheet consisting of construct, content, and language validity which gets mode = 4, so that the four-tier multiple choice instrument is said to be valid. Practicality is obtained from a learner response questionnaire supported by a learner activity observation sheet. Practicality in terms of the student's response questionnaire is 84% with a very practical category, while the student activity observation sheet gets mode = 1, so the diagnostic test instrument is said to be practical. Effectiveness is obtained from the diagnostic test instrument reliability test. The Cronbach alpha value obtained in the reliability test was 0.798, so the diagnostic test instrument developed was declared reliable. Based on the results of validity, practicality, and effectiveness, the four-tier multiple choice diagnostic test instrument is declared suitable for use.

Eco‐Friendly Analytical Approaches for the Quantification of Molnupiravir and Favipiravir Using Capillary Zone Electrophoresis and Derivative Ratio Spectrophotometry

AbstractDesigning new validated analytical procedures with a focus on many objectives, such as simplicity, environmental friendliness, analytical effectiveness, and sustainability, has grown to be a top priority in quality control departments. Applying green and white analytical chemistry concepts is no longer a luxury. In this report, two new approaches, Capillary Zone Electrophoresis (CZE) with Photo Diode Array (PDA) detection and derivative ratio spectrophotometric methods, are established and validated for the simultaneous analysis of molnupiravir (MLP) and favipiravir (FAV) in bulk, single dosage forms, and their expected combined dosage forms. For the two drugs, linearity ranges of 5–50 μg/mL and 1–30 μg/mL were achieved using the CZE and spectrophotometric methods, respectively. Both techniques have been validated and used for the estimation of the two medications in lab‐made capsules in accordance with the International Council for Harmonization's (ICH) recommendations. Seven assessment models were used to evaluate the greenness and sustainability of the introduced approaches compared to three previously published HPLC, chemometric, and HPTLC techniques. ChlorTox and BAGI tools are applied for the first time for the evaluation of an analytical procedure. Higher green and sustainable qualities were declared by suggested approaches than by earlier ones.

Rapid and efficient synthesis of energy-saving cool pigments and environmental restoration materials using rare earth secondary resources

This paper proposes a method for the short-process recovery and reuse of rare earth secondary resources. Low-value rare earth polishing powder waste (WP), trichromatic phosphor waste (WT), NdFeB permanent magnetic waste (WN), and SmCo permanent magnetic waste (WS) were used as the raw materials. Based on the concept of combinatorial chemistry, energy-efficient cool pigments and environmental remediation materials were synthesized by a solid-phase method. The results showed that the synthesized materials had fluorite-type and garnet-type structures. In terms of cool pigments, doping with different rare earth permanent magnets can enrich the color (including yellow, green, brown, gray, and blue) and cause fluctuations in the near-infrared (NIR) reflectance (59.05–99.54 %) and NIR solar reflectance (55.32–95.64 %). Yellow fluorite-type pigments (WP: WT = 1:1) have the highest NIR reflectance (R = 99.54 %), while brown fluorite-type pigments (WP: WN = 1:0.1) and blue garnet-type pigments (WP:WS = 1:0.1) have relatively high NIR reflectance, 88.18 % and 59.30 %, respectively. The synthesized pigments possessed better chemical stabilities and thermal insulation performance. In terms of environmental remediation materials, the adsorption capacities of fluorite-type materials for F− and PO43− can reach 84.03 mg/g and 85.3 mg/g, respectively. In summary, materials synthesized from rare earth waste exhibit excellent potential for use in energy-efficient wastewater treatment and promote the sustainable utilization of secondary rare earth resources.

고교학점제에서 과학 선택 과목의 경향성 분석

Objectives This study investigated and analyzed the tendency of students to choose subjects and the tendency of chemical academic achievement according to science subject selection in the high school credit system. Methods For six months, from March to August 2020, 339 sophomores of S High School located in Gyeongnam were surveyed and analyzed for their perception of subject selection. Among them, a questionnaire was devel-oped to find out the perception of the content of chemistry subjects, and a questionnaire was conducted on 78 people who agreed to participate in the study. In order to analyze the tendency of chemical academic achievement according to science subject selection in the high school credit system, descriptive statistics, cross-analysis, and nonparametric tests were performed with the SPSS 28 program. Results Students selected many of the science elective subjects in the order of 'Chem-Phys-Bio,' 'Chem-Phys-Earth,' and 'Chem-Bio-Earth.' In the content and concept of the Chemistry I subject, students were found to have difficulty understanding concepts such as 'mole,' 'chemical reaction formula,' 'orbital,' etc., and the 'Chem-Phys-Earth' subject group was found to have the most difficulty in understanding the concept of 'mole.' In addition, in the comparison of achievement by elective subject group, the 'Chem-Phys-Bio' subject group showed the highest chemical academic achievement and the 'Chem-Phys-Earth' subject group showed the low-est achievement. Conclusions In the high school credit system, students chose the Science I course independently, but many stu-dents were found to have insufficient understanding of the basic concept of Chemistry I. Therefore, in terms of understanding the concept of chemistry, it is essential to design a teaching-learning process by level so that stu-dents can better understand the basic concept of Chemistry I in the high school credit system.

Effect of Wait-Time on Attitude and Retention of Senior Secondary School Students to Learning Chemistry Concepts

Effect of Wait-Time on Attitude and Retention of Senior Secondary School Students to Learning Chemistry Concepts

The effectiveness of natural indigo/kaolinite composite powder in the development of latent fingermarks

BackgroundComposites are materials that have multiple phases and have attracted much attention as they are able to improve physical and chemical properties of an isolated material. In this sense, these composites are commonly used as key components for two purposes: coloring and improving the operational properties; besides that, they have alternative synthesis routes that respect the principles of green chemistry. Thus, this reports the development of a new composite using natural products, indigo and kaolinite, for application in papilloscopy as a new nontoxic fingermark developer.ResultsThe composite was obtained via green procedures and was characterized by spectroscopic and chromatographic techniques. Thus, to investigate the potential of the material as a fingermark developer, different techniques were applied such as depletion, aging, comparison with commercial powder, and development of latent fingermarks on different surfaces. Tests revealed that the composite presented good contrast and adhesion with the latent fingermarks, even after 15 days of deposition.ConclusionsThis study presents a natural indigo/kaolinite composite powder that showed similar or higher efficiency when compared to the commercial fingerprint powder and was able to develop identifiable natural and sebaceous fingermarks.Key points• A composite was formed from eco-friendly materials.• The composite formation follows the concepts of green chemistry and low cost.•The composite was applied as a latent fingermark developer.

Interpretation of molecular electron transport in ab initio many-electron framework incorporating zero-point nuclear motion effects.

A computational methodology, founded on chemical concepts, is presented for interpreting the role of nuclear motion in the electron transport through single-molecule junctions (SMJ) using many-electron ab initio quantum chemical calculations. Within this approach the many-electron states of the system, computed at the SOS-ADC(2) level, are followed along the individual normal modes of the encapsulated molecules. The inspection of the changes in the partial charge distribution of the many-electron states allows the quantification of the electron transport and the estimation of transmission probabilities. This analysis improves the understanding of the relationship between internal motions and electron transport. Two SMJ model systems are studied for validation purposes, constructed from a conductor (BDA, benzene-1,4-diamine) and an insulator molecule (DABCO, 1,4-diazabicyclo[2.2.2]octane). The trends of the resulting transmission probabilities are in agreement with the experimental observations, demonstrating the capability of the approach to distinguish between conductor and insulator type systems, thereby offering a straightforward and cost-effective tool for such classifications via quantum chemical calculations.

The past is the future: from natural acid-base indicators to natural reagents in sustainable analytical chemistry

Abstract This article reviews the use of natural resources in analytical chemistry throughout history. Plant extracts were employed as indicators in chemistry for identifying the acidity or alkalinity of liquids as early as the 1650s. Later, as the industrial revolution altered people’s lives, synthetic chemicals were used instead. Modern techniques of analysis have replaced conventional ones as a result of advancements in physics and technology. The industrial revolution was an era of excitement until the toxic pollutants released from industries severely damaged people and the environment. The concepts of green chemistry and green analytical chemistry were proposed as potential solutions to the problems. The use of natural extracts as chemical analysis reagents has been reconsidered recently as a sustainable alternative. While new technologies such as artificial intelligence (AI) will influence future trends in analytical chemistry development, the primary goal is to move toward sustainable analytical chemistry, which includes using natural reagents and reducing the amount of chemicals consumed and waste produced.