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The mechanism of nucleation, steady-state growth, and repair is investigated for an oxygen evolving catalyst prepared by electrodeposition from Co(2+) solutions in weakly basic electrolytes (Co-OEC). Potential step chronoamperometry and atomic force microscopy reveal that nucleation of Co-OEC is progressive and reaches a saturation surface coverage of ca. 70% on highly oriented pyrolytic graphite substrates. Steady-state electrodeposition of Co-OEC exhibits a Tafel slope approximately equal to 2.3 × RT/F. The electrochemical rate law exhibits a first order dependence on Co(2+) and inverse orders on proton (third order) and proton acceptor, methylphosphonate (first order for 1.8 mM ≤ [MeP(i)] ≤ 18 mM and second order dependence for 32 mM ≤ [MeP(i)] ≤ 180 mM). These electrokinetic studies, combined with recent XAS studies of catalyst structure, suggest a mechanism for steady state growth at intermediate MeP(i) concentration (1.8-18 mM) involving a rapid solution equilibrium between aquo Co(II) and Co(III) hydroxo species accompanied with a rapid surface equilibrium involving electrolyte dissociation and deprotonation of surface bound water. These equilibria are followed by a chemical rate-limiting step for incorporation of Co(III) into the growing cobaltate clusters comprising Co-OEC. At higher concentrations of MeP(i) ([MeP(i)] ≥ 32 mM), MePO(3)(2-) equilibrium binding to Co(II) in solution is suggested by the kinetic data. Consistent with the disparate pH profiles for oxygen evolution electrocatalysis and catalyst formation, NMR-based quantification of catalyst dissolution as a function of pH demonstrates functional stability and repair at pH values >6 whereas catalyst corrosion prevails at lower pH values. These kinetic insights provide a basis for developing and operating functional water oxidation (photo)anodes under benign pH conditions., (© 2012 American Chemical Society)

Since Breslow's initial report on the thiamine mode of action, the study of catalytic acyl carbanion processes has been an area of immense interest. With the advent of azolylidene catalysis, a plethora of reactivtiy has been harnessed, but the crucial nucleophilic intermediate proposed by Breslow had never been isolated or fully characterized. Herein, we report the isolation and full characterization of nitrogen analogues of the Breslow intermediate. Both stable and catalytically relevant, these species provide a model system for the study of acyl carbanion and homoenolate processes catalyzed by triazolylidene carbenes., (© 2012 American Chemical Society)

Virtual simulations are a very useful educational resource to improve the teaching of chemistry. Their use makes it possible to facilitate the comprehension of concepts, promotes the development of scientific competences and even improves student attitudes toward chemistry. However, it is important to point out that a simulation by itself is not enough to improve student learning. Methodological design is a crucial aspect in order for its classroom use to be significant. Simulations must form part of an instructional sequence that promotes said learning, and thus the role of the instructor is key. This work conducts a systematic review with the aim of analyzing how to apply the use of simulations in the teaching of chemistry in secondary schools, delving deeper into the way in which simulations are used from a methodological perspective, in order to improve the learning processes and results. In this sense, it was found that there is an improvement in learning on both the level of content comprehension and in scientific competences. Guided research is also identified as the most effective methodology for the application of simulations in the classroom. With a look to the future, it is suggested that there is a need to conduct research on the continued use of simulations in the classroom, as well as their characteristics and the instructional methods used.

Mixed results have been reported on the correlation between clickers and performance. This study investigates the usage of clickers in a voluntary context to answer in-class questions in a General Chemistry class. Scores on an internal chemistry placement exam were used to estimate cognitive ability, as a factor that students can no longer control, and average participation on clicker questions was considered as a behavioral aspect that students are able to change. While placement exam scores and clicker usage do not correlate with each other, both positively correlate with performance (midterm average grades and final course grades) in the cohorts of this study (2017, 2018, and 2019). Independent of placement exam scores, students who answered more clicker questions performed better on midterm exams and had a higher final course grade. Students who obtained course grades of A, B, or C answered more clicker questions on average (68% of questions) than students who earned course grades of D or F (51% of questions). Those who answered more than the average number of the clicker questions were at least 2.6 times more likely to achieve course proficiency. These results suggest that students who choose to engage by answering questions in class (answer correctness not required) are more likely to perform well in general chemistry courses, regardless of cognitive ability.

Students come into the classroom with a variety of background knowledge. Therefore, it is imperative that educators are able to help all students, regardless of their familiarity with the content. Since it can be challenging for some large enrollment classes to schedule recitation classes after lectures due to logistical constraints, this study attempts to determine if there are differences in performance based on when content is introduced first, recitation or lecture. This study found that students who were introduced to content in recitation before a lecture typically scored statistically higher across three mid-term exams, in a first-term general chemistry course. This difference in performance suggests that students who are introduced to content in recitation, versus simply hearing about a topic in a lecture, might get more out of the lecture, thus leading to higher performance on exams. Students who are introduced to topics that are tested by way of definition-based questions or basic calculations benefit from being introduced to this content in recitation before the lecture. However, when introducing more challenging and abstract chemistry topics, our results indicate it may benefit students to be introduced to these topics in the lecture first, so they can begin developing their conceptual understanding in the lecture.

Students are encouraged to develop a set of scientific skills and disciplinary practices common across the STEM disciplines. These skills (scientific inquiry, quantitative skills, laboratory and computational skills, communication skills, teamwork/interpersonal skills, interdisciplinary competency) are highlighted as important in discipline-based guiding documents -- biology (Vision and Change in Undergraduate Biology Education: A Call to Action), chemistry (American Chemical Society Guidelines and Evaluation Procedures for Bachelor's Degree Programs), and mathematics (A Common Vision for Undergraduate Mathematical Sciences Programs in 2025) -- for undergraduate teaching of biology, chemistry, and mathematics, and for the professional success of STEM college graduates. To promote interdisciplinary teaching and learning of STEM, we present a comprehensive comparison of the different disciplines' competency statements for undergraduate education. This organization and comparison of commonalities in scientific skills and disciplinary practices can be used by faculty and departments to come together to break down traditional silos, help their students more easily apply learning from one STEM discipline to another, and to create institutional change.

Peer Instruction (PI), a student-centred teaching method, engages students during class through structured, frequent questioning, facilitated by classroom response systems. The central feature of PI is the ConcepTest, a question designed to help resolve student misconceptions around the subject content. Within our coordination chemistry PI session, we provide students two opportunities to answer each question -- once after a round of individual reflection, and then again after a round of augmented reality (AR)-supported peer discussion. The second round provides students with the opportunity to "switch" their original response to a different answer. The percentage of right answers typically increase after peer discussion: most students who answer incorrectly in the individual round switch to the correct answer after the peer discussion. For the six questions posed, we analysed students' discussions, in addition to their interactions with our AR tool. Furthermore, we analyse students' self-efficacy, and how this, in addition to factors such as ConcepTest difficulty influence response switching. For this study, we found that students are more likely to switch their responses for more difficult questions, as measured using the approach of Item Response Theory. Students with high pre-session self-efficacy switched from right-to-wrong (p < 0.05) and wrong-to-different wrong less often, and switched from wrong-to-right more often than students with low self-efficacy. Students with a low assessment of their problem solving and science communication abilities were significantly more likely to switch their responses from right to wrong than students with a high assessment of those abilities. Analysis of dialogues revealed evidence of the activation of knowledge elements and control structures.

Engaging undergraduate students in authentic research is a powerful pedagogical tool for undergraduate education. The key to maximizing the benefit of research experiences is a proper mentoring relationship. Here, we present the findings of international chemistry and biology undergraduate research experiences studied via a critical qualitative methodology to understand the cross-cultural mentoring relationship. This study demonstrates that mentors and students came into a mentoring relationship with different sets of normative infrastructures, which entail their assumptions about the purposes, values, and beliefs of undergraduate research. Their normative infrastructures came from their cultural backgrounds and prior scientific training. Positive experiences of participants are attributed to the inherent characteristics of students, mentors, or the program as well as aligned settings. On the other hand, negative experiences are associated with misaligned settings. We propose that understanding mentoring relationships may uncover new ideas to improve mentors' and students' experiences within undergraduate scientific research.

This research focused on the impact of research- and assessment-based instruction on senior high school students' achievement in selected chemistry topics. A 3 × 2 × 2 pre-test and post-test control group in a quasi-experimental research design was used on a population of Grade 11 chemistry students in Ojo Local Government Area of Lagos state. Two schools (one public and one private) were randomly assigned to each of the treatments. A sample of 240 chemistry students was used. Three research questions were answered and five hypotheses were tested. The reliability coefficient of the "Chemistry achievement test" was found to be 0.770 using the Kuder-Richardson Formula 20. Research-based, assessment-based, and conventional instruction manuals were also developed. The data collected were analyzed using descriptive statistics and analysis of covariance. It was found that the impact of assessment- and research-based instruction on senior high school students' achievement in the selected topics was significant (F (2,227) = 49.214, p < 0.050). It was also found that the students exposed to the assessment-based instructional mode had a higher achievement than those in the research-based and conventional groups. Male chemistry students were found to benefit more than the female students after being exposed to research- and assessment-based instructional modes. It is, therefore, recommended that assessment- and research-based instructional modes be used to teach the selected chemistry topics to enhance effective learning.

The concealment of assets is a critical challenge in financial fraud and asset recovery investigations, posing significant obstacles for creditors and regulatory authorities. National governments commonly possess the necessary data for detecting and combating this type of fraud, typically related to personal data and asset ownership. However, this information is often dispersed across different departments within the same government and sometimes in databases shared by other countries. This leads to difficulty semantically integrating this large amount of data in various formats and correlating entities through identifying hidden relationships, which are essential in this type of analysis. In this regard, this work proposes an ontology to support the data integration process in the domain of asset concealment and recovery and fill the gap in the existence of a public ontology for this domain. The applicability of this ontology in the context of integration between data from different departments and countries was validated. The use of the ontology in a pilot project in the context of a tool for investigating this type of fraud was conducted with a Brazilian government agency, and the users validated its applicability. Finally, a new method for constructing ontologies is proposed. The proposed process was evaluated during the asset concealment ontology building and proved to be more suitable than the similar processes analyzed concerning the partial reuse of existing ontologies and the construction of ontologies for data with a transnational scope.

Candida auris and Candida haemulonii are two emerging opportunistic pathogens that have caused an increase in clinical cases in the recent years worldwide. The differentiation of some Candida species is highly laborious, difficult, costly, and time-consuming depending on the similarity between the species. Thus, this study aimed to develop a new, faster, and less expensive methodology for differentiating between C. auris and C. haemulonii based on near-infrared (NIR) spectroscopy and multivariate analysis. C. auris CBS10913 and C. haemulonii CH02 were separated in 15 plates per species, and three isolated colonies of each plate were selected for Fourier transform near-infrared (FT-NIR) analysis, totaling 90 spectra. Subsequently, principal component analysis (PCA) and variable selection algorithms, including the successive projections algorithm (SPA) and genetic algorithm (GA) coupled with linear discriminant analysis (LDA), were employed to discern distinctive patterns among the samples. The use of PCA, SPA, and GA algorithms associated with LDA achieved 100% sensitivity and specificity for the discriminations. The SPA-LDA and GA-LDA algorithms were essential in selecting the variables (infrared wavelengths) of most importance for the models, which could be attributed to binding of cell wall structures such as polysaccharides, peptides, proteins, or molecules resulting from yeasts’ metabolism. These results show the high potential of combined FT-NIR and multivariate analysis techniques for the classification of Candida-like fungi, which can contribute to faster and more effective diagnosis and treatment of patients affected by these microorganisms.

This article provides a comprehensive review of the state-of-the-art technology of polymeric mixed-matrix membranes for CO2/CH4 separation that can be applied in medium, small, and domestic biogas systems operating at low pressures (0.2–6 kPa). Critical data from the latest publications of CO2/CH4 separation membranes were analyzed, considering the ratio of CO2/CH4 permeabilities, the CO2 selectivity, the operating pressures at which the membranes were tested, the chemistry of the polymers studied and their gas separation mechanisms. And the different nanomaterials as fillers. The intrinsic microporous polymers (PIMs) were identified as potential candidates for biomethane purification due to their high permeability and selectivity, which are compatible with operation pressures below 1 bar, and as low as 0.2 bar. This scenario contrasts with other polymers that require pressures above 1 bar for operation, with some reaching 20 bar. Furthermore, the combination of PIM with GO in MMMs was found to not influence the permeability significantly, but to contribute to the membrane stability over time, by preventing the structural collapse of the membrane caused by aging. The systematic analysis here presented is a valuable resource for defining the future technological development of CO2/CH4 separation membranes for biogas biorefining.

An ability to engage in system thinking is necessary to understand complex problems. While many pre-college students use system modeling tools, there is limited evidence of student reasoning about causal relationships that interact in diverging and converging chains, and how these affect system behavior. A chemistry unit on gas phenomena was implemented in two successive years with 73 high school students. Although the phenomena could be explained with simple linear causal reasoning, many student models included surprising and problematic causal chains and non-linear patterns. Commonly, discussion about student models in classrooms and interviews focuses on individual causal relationships. However, in our experience, this can fail to bring to the surface conceptual issues that result from the combination of two or more relationships. Using interview data from 19 students, we looked for instances where students explained their conceptions and we identified questioning strategies that elicited these explanations. Questions that appeared most productive asked about distal relationships between nonadjacent variables in model substructures of three to four variables. In response to these questions, eight students expressed their thinking about relationship combinations, including unexpected reasoning that had not emerged during classroom instruction. Using exemplars from three interviews, we argue that students engage in complex causal reasoning that may be implicit and unexpected, and that if this is not recognized, it cannot be responded to during instruction. We suggest that using model substructures as a mutual visual referent along with a simple questioning strategy shows promise for helping students make their causal reasoning explicit.

Abstract Bivalent molecules consisting of groups connected through bridging linkers often exhibit strong target binding and unique biological effects. However, developing bivalent inhibitors with the desired activity is challenging due to the dual motif architecture of these molecules and the variability that can be introduced through differing linker structures and geometries. We report a set of alternatively linked bivalent EGFR inhibitors that simultaneously occupy the ATP substrate and allosteric pockets. Crystal structures show that initial and redesigned linkers bridging a trisubstituted imidazole ATP-site inhibitor and dibenzodiazepinone allosteric-site inhibitor proved successful in spanning these sites. The re-engineered linker yielded a compound that exhibited significantly higher potency (~60 pM) against the drug-resistant EGFR L858R/T790M and L858R/T790M/C797S, which was superadditive as compared with the parent molecules. The enhanced potency is attributed to factors stemming from the linker connection to the allosteric-site group and informs strategies to engineer linkers in bivalent agent design.

The use of seashells as a partial substitute for cement in construction not only offers an innovative solution for marine waste management but also contributes to reducing the carbon footprint of the cement industry, decreasing the CO2 emissions associated with cement production and promoting more sustainable construction practices. This study addresses the mechanical behavior of mortar specimens with partial cement replacement using crushed Biobío region clam shells, both calcined and uncalcined, at substitution rates of 5% and 10%. This approach allows the analysis of their effect on the mechanical strength and properties of the mortar, which has not been widely investigated in the Chilean context or with this particular species of shell. For the mechanical characterization of the specimens, tensile flexural tests and compressive tests were were conducted at ages of 3, 7, 14, and 28 days. The compressive strengths of the samples that incorporated calcined residue with partial cement replacements of 5% and 10% were 83.69% and 78.27%, respectively, of the average strength of 20.97 MPa reached by the standard sample. In terms of their tensile flexural strength, these samples reached average strengths of 104.31% and 104.04% of the strength of 12.12 MPa obtained by the standard sample. In the case of the uncalcined samples, the 5% and 10% replacements reached 103.55% and 102.64% of the tensile strength of 15.54 MPa obtained by the standard sample, while they reached 92.32% and 80.07% of the compressive strength of 27.81 MPa achieved by the standard sample. From these results, it is determined that the calcined shells did not improve the mechanical resistance of the mortar, suggesting that the calcination process must be studied in depth.

Wire-based directed energy deposition (WDED) is an emerging additive manufacturing process garnering significant attention due to its potential for fabricating metal components with tailored mechanical and microstructural properties. This study reviews the WDED process, focusing on fabrication techniques, mechanical behaviors, microstructural characteristics, and quality enhancement methods. Utilizing data from the Web of Science, the study identifies leading countries in WDED research and highlights a growing interest in the field, particularly in materials engineering. Stainless steel, titanium, aluminum, and copper-based alloys are prominent materials for WDED applications. Furthermore, the study explores post-processing techniques such as machining, heat treatment, and surface finishing as integral steps for quality enhancement in WDED components.

Nanomedicine holds great potential for revolutionizing medical treatment. Ongoing research and advancements in nanotechnology are continuously expanding the possibilities, promising significant advancements in healthcare. To fully harness the potential of nanotechnology in medical applications, it is crucial to conduct safety evaluations for the nanomedicines that offer effective benefits in the preclinical stage. Our recent efficacy studies indicated that rapamycin perfluorocarbon (PFC) nanoparticles showed promise in mitigating cisplatin-induced acute kidney injury (AKI). As cisplatin is routinely administered to ovarian cancer patients as their first-line chemotherapy, in this study, we focused on evaluating the safety of rapamycin PFC nanoparticles in mice bearing ovarian tumor xenografts. Specifically, this study evaluated the effects of repeat-dose rapamycin PFC nanoparticle treatment on vital organs, the immune system, and tumor growth and assessed pharmacokinetics and biodistribution. Our results indicated that rapamycin PFC nanoparticle treatment did not cause any detectable adverse effects on cardiac, renal, or hepatic functions or on splenocyte populations, but it reduced the splenocyte secretion of IL-10, TNFα, and IL12p70 upon IgM stimulation. The pharmacokinetics and biodistribution results revealed a significant enhancement in the delivery of rapamycin to tumors by rapamycin PFC nanoparticles, which, in turn, led to a significant reduction in ovarian tumor growth. Therefore, rapamycin PFC nanoparticles have the potential to be clinically beneficial in cisplatin-treated ovarian cancer patients.

Indazoles have previously been identified as molecules with antiprotozoal activity. In this study, we evaluate the in vitro activity of thirteen 3-alkoxy-1-benzyl-5-nitroindazole derivatives (series D) against L. amazonensis, L. infantum, and L. mexicana. In vitro, cytotoxicity against mouse peritoneal macrophages and growth inhibitory activity in promastigotes were evaluated for all compounds, and those showing adequate activity and selectivity were tested against intracellular amastigotes. Transmission and scanning electron microscopy were employed to study the effects of 3-alkoxy-1-benzyl-5-nitroindazole and 2-benzyl-5-nitroindazolin-3-one derivatives on promastigotes of L. amazonensis. Compounds NV6 and NV8 were active in the two life stages of the three species, with the latter showing the best indicators of activity and selectivity. 3-alkoxy-1-benzyl-5-nitroindazole derivatives (series D) showed in vitro activity comparable to that of amphotericin B against the promastigote stage of Leishmania spp. Two compounds were also found to be active the amastigote stage. Electron microscopy studies confirmed the antileishmanial activity of the indazole derivatives studied and support future research on this family of compounds as antileishmanial agents.

Diffusion and immobilization of molecules in biomembranes are essential for life. Understanding it is crucial for biomimetic approaches where well-defined substrates are created for live cell assays or biomaterial development. Here, we present biomimetic model systems consisting of a supported lipid bilayer and membrane coupled proteins to study the influence of lipid–lipid and lipid–protein interactions on membrane mobility. To characterize the diffusion of lipids or proteins, the continuous photobleaching technique is used. Either Neutravidin coupled to DOPE-cap-Biotin lipids or GFP coupled to DOGS-NTA lipids is studied at 0.005–0.5 mol% concentration of the linker lipid. Neutravidin creates mobile obstacles in the membrane, while GFP coupling results in immobile obstacles. By actin filament coupling to Neutravidin-lipid complexes, obstacles are crosslinked, resulting in lipid mobility reduction along with the appearance of a membrane texture. Theoretical considerations accurately describe lipid diffusion changes at high obstacle concentration as a function of obstacle size and viscous effects. The mobility of membrane lipids depends on the concentration of protein-binding lipids and on the concentration and charge of the coupled protein. Next to diffusion and friction coefficients, we determine the effective obstacle size as well as a charge-dependent effect that dominates the decrease in lipid mobility.

This research aimed to use students' modeling processes as a means of scientific inquiry. Students constructed models to explain the interactions between felodipine R and S and protein. The approach encouraged active student participation in molecular interaction modeling and offered students a "model-based teaching" experience for developing explanations of chemical phenomena. The concept is built on four structural concepts in chemistry-molecular interactions, Gibbs free energy, chemical equilibria, and optical isomerism. This framework enabled the examination of medical students' ability to integrate general chemistry for developing models that can explain drug interactions. This proposal is part of a research cycle using design-based research for a qualitative methodology centered on modeling. This research provides evidence that constructivist teaching is possible as a model-based intervention in the classrooms, measured in a medical training context, allowing students to develop, evaluate, and constantly revise their chemical understanding.

This research is a large study over an extended period of time involving hundreds of general chemistry students and multiple instructors at the US Naval Academy. The purpose was to investigate whether a combination of clicker content and confidence questions would improve the performance and metacognition of students of different achievement groups (top, middle, bottom). Results showed no statistical difference in exam achievement between students who used clickers and those who did not when other active teaching methods were employed in both groups. Within the clicker participants, statistical differences in confidence on clicker questions were found by student achievement group, question type (algorithmic and conceptual), and question difficulty for both semesters of general chemistry. Students in the top achievement group were the most confident. All students were more confident on algorithmic and easy questions, though a significant interaction was found between question type and difficulty in the second semester. Metacognition was measured by calibration (confidence when the answer is corrector lack of confidence when incorrect). Overall, students of all achievement groups were well calibrated with students in the top group being confident in correct answers and students in the bottom group nonconfident within correct answers. Students in the middle group displayed calibration between those of the top and bottom groups. Evidence of calibration for middle and bottom students may indicate the beginning of metacognitive awareness. A positive trend was found in student perceived value of confidence questions over the two semesters of general chemistry.

Learning management systems play a crucial role in addressing pedagogical challenges imposed by the COVID-19 pandemic. The solutions provided by the learning management systems (LMS) facilitated online instructions and helped form a community of learning and support. With the rapid increased usage during the pandemic and the return to face-to-face post-pandemic, an in-depth analysis on lasting changes in students' engagement and the instructors' use of the systems during and after the pandemic is needed. This study aims at providing the analysis results on the differential usage of the learning management systems in a chronological time frame and on a course-level-specific aspect. Analysis conducted on the LMS usage data of chemistry courses between Fall 2019 and Fall 2021 suggests unique patterns, depending on the course levels. The extent of students' interaction with peers and course materials varied for different course levels. The degree of usage of learning management systems by instructors also depended on the course levels. Instructors in lower-level courses (1000 and 2000 level courses) continued to use learning management systems extensively after the pandemic, while instructors in upper-level courses (3000 and 4000 level courses) rebounded to their pre-pandemic level of usage after resuming face-to-face instructions.

The two-semester General Chemistry laboratory sequence for nonchemistry majors at James Madison University has recently made the transition from expository, confirmation experiments to project-based (first semester) and research-based (second semester) curricula; this narrative will describe the development and current state of the Brewing Science (BrewSci) second-semester course. This high-enrollment service course with typically [approximately]25 sections (maximum enrollment of 24 students per section) offered during the regular two-semester school year was designed to leverage the skills obtained in a research-based environment: problem-solving, creativity, teamwork, communication, etc. The synthesis (brewing) and analysis of beer was selected as a vehicle for the learning goals due to the range of variables that can be manipulated, the wealth of relevant chemistry/biochemistry content suitable for a second-semester General Chemistry course, and the relative safety of the brewing process. Teaching supports, including trained undergraduate Learning Assistants, have been developed and employed to ensure the course can be taught by any of the rotating cohort of full-time or part-time faculty members. Analysis of course success rates (students earning a C- or higher) and DFW rates indicates improved student outcomes. Further, preliminary analysis of student survey data indicates improved student perceptions of their own abilities to think and act as scientists. Instructors corroborated these findings in a separate survey. Following the successful establishment of the BrewSci version of the General Chemistry 2 lab, the same curriculum development model is now being leveraged to expand offerings to other areas of faculty and student interest.

In this article, we describe a fully computational laboratory exercise that results in an increase of students' understanding of what quantum chemical geometry optimization calculations are doing to find minimum energy structures. This laboratory exercise was conducted several times over multiple years at a small private undergraduate institution, St. Bonaventure University. Through this experiment, physical chemistry undergraduate students are exposed to chemical problems for which computations provide a necessary supplement to chemical intuition, thus cementing the importance of computational work in contemporary chemistry. Students apply their understanding of geometry optimizations to problems of complex 3-D molecular structures that stretch their intuition, including the geometries and isomers of "closo"-carboranes and of the hexamer of the cocatalyst methylaluminoxane. Students are also exposed to vibrational frequency calculations as a diagnostic tool for determining whether structures represent energetic minima or transition states, and they are exposed to the vibrational zero-point energy correction.

The undergraduate transfer process has well-documented challenges, especially for those who identify with groups historically excluded from science, technology, engineering, and mathematics (STEM) programs. Because transfer students gain later access to university networking and research opportunities than first-time-in-college students, transfer students interested in pursuing postbaccalaureate degrees in chemistry have a significantly shortened timeline in which to conduct research, a crucial component in graduate school applications. Mentorship programs have previously been instituted as effective platforms for the transfer of community cultural wealth within large institutions. We report here the design, institution, and assessment of a near-peer mentorship program for transfer students, the Transfer Student Mentorship Program (TSMP). Founded in 2020 by graduate students, the TSMP pairs incoming undergraduate transfer students with current graduate students for personalized mentorship and conducts discussion-based seminars to foster peer relationships. The transfer student participants have access to a fast-tracked networking method during their first transfer semester that can serve as a route for acquiring undergraduate research positions. Program efficacy was assessed via surveys investigating the rates of research participation and sense of belonging of transfer students. We observed that respondents that participated in the program experienced an overall improvement in these measures compared to respondents who did not. Having been entirely designed, instituted, and led by graduate students, we anticipate that this program will be highly tractable to other universities looking for actionable methods to improve their students' persistence in pursuing STEM degrees.

We analyzed the influence of exercise order using the bench press and squat as the first or second exercise of the session on velocity performance. Ten male trained individuals (20.9 ± 0.7 years) randomly performed two protocols of three sets of six repetitions at 80% of their one-repetition maximum with different exercise sequences: the bench press followed by the squat (BP + S) and the squat followed by the bench press (S + BP). A linear velocity transducer attached to the Smith machine barbell measured the mean propulsive velocity (MPV), peak velocity (PV), and time to peak velocity. Additionally, blood lactate and heart rate were measured. Regarding the bench press, differences were found in the MPV in the first (BP + S: 0.50 ± 0.07 m·s−1 vs. S + BP: 0.42 ± 0.08 m·s−1; p = 0.03, g = 0.72) and second sets (0.50 ± 0.06 m·s−1 vs. 0.42 ± 0.07 m·s−1; p = 0.03, g = 0.73), and in the PV in the second set (0.74 ± 0.09 m·s−1 vs. 0.63 ± 0.09 m·s−1; p = 0.02, g = 0.86). Regarding the squat, although the S + BP sequence tended to show higher velocities, no significant differences were found between protocols. These results showed that squatting first decreased subsequent bench press velocity performance. On the other hand, squat velocity performance was not impaired when preceded by the bench press.

A new series of flexible polyamide (PA) aerogels was synthesized using terephthaloyl chloride (TPC), 2,2′-dimethylbenzidine (DMBZ) and cross-linked with an inexpensive, commercially available tri-isocyanate (Desmodur N3300A) at polymer concentrations of 6–8 wt.% total solids and repeating units, n, from 30 to 60. The cross-linked DMBZ-based polyamide aerogels obtained, after supercritically drying using liquid CO2, had shrinkages of 19–27% with densities ranging from 0.12 g/cm3 to 0.22 g/cm3, porosity and surface areas up to 91% and 309 m2/g, respectively, and modulus values ranging from 20.6 to 109 MPa. Evidence suggests that a higher flexibility could be achieved using DMBZ in the polyamide backbone with N3300A as a cross-linker, when compared to previously reported TPC-mPDA-BTC PA aerogels, N3300A-polyimide aerogels, and N3300-reinforced silica aerogels.

A custom tribometer was developed to measure friction coefficient and temperature in high-pressure, low-velocity conditions, specifically for studying copper alloys used in sliding bearings for heavy equipment. Using this equipment, two commercial alloys were tested to evaluate friction coefficient, specific wear rate, thermal behavior, and subsurface strain. The results, validated through comparison with reference commercial equipment and uncertainty estimates, met acceptable criteria for tribological tests, with an uncertainty estimate value for the friction coefficient of 0.4%. The tribological tests confirmed the importance of solid lubrication in high-lead bronzes and the high wear resistance of Cu-Al-Ni-Fe alloys, which directly influence temperature, subsurface strain, and respective wear mechanisms.

(1) Background: Tennis has changed toward power-driven gameplay, demanding a nuanced understanding of performance factors. This review explores the role of machine learning in enhancing tennis performance. (2) Methods: A systematic search identified articles utilizing machine learning in tennis performance analysis. (3) Results: Machine learning applications show promise in psychological state monitoring, talent identification, match outcome prediction, spatial and tactical analysis, and injury prevention. Coaches can leverage wearable technologies for personalized psychological state monitoring, data-driven talent identification, and tactical insights for informed decision-making. (4) Conclusions: Machine learning offers coaches insights to refine coaching methodologies and optimize player performance in tennis. By integrating these insights, coaches can adapt to the demands of the sport by improving the players’ outcomes. As technology progresses, continued exploration of machine learning’s potential in tennis is warranted for further advancements in performance optimization.

The advent of fiber optic technology in geophysics exploration has grown in its use in the exploration, production, and monitoring of subsurface environments, revolutionizing the way data are gathered and interpreted critically to speed up decision-making and reduce expense and time. Distributed Acoustic Sensing (DAS) has been increasingly utilized to build relationships in complex geophysics environments by utilizing continuous measurement along fiber optic cables with high spatial resolution and a frequency response of up to 10 KHz. DAS, as fiber optic technology examining backscattered light from a laser emitted inside the fiber and measuring strain changes, enables the performance of subsurface imaging in terms of real-time monitoring for Vertical Seismic Profiling (VSP), reservoir monitoring, and microseismic event detection. This review examines the most widely used fiber optic cables employed for DAS acquisition, namely Single-Mode Fiber (SMF) and Multi-Mode Fiber (MMF), with the different deployments and scopes of data used in geophysics exploration. Over the years, SMF has emerged as a preferred type of fiber optic cable utilized for DAS acquisition and, in most applications examined in this review, outperformed MMF. On the other side, MMF has proven to be preferable when used to measure distributed temperature. Finally, the fiber optic cable deployment technique and acquisition parameters constitute a pivotal preliminary step in DAS data preprocessing, offering a pathway to improve imaging resolution based on DAS measurement as a future scope of work.

Hybrid scaffolds that are based on PLA and PLA/PMMA with 75/25, 50/50, and 25/75 weight ratios and functionalized with 10 wt.% of bioglass nanoparticles (n-BG) were developed using an electrospinning technique with a chloroform/dimethylformamide mixture in a 9:1 ratio for bone tissue engineering applications. Neat PLA and PLA/PMMA hybrid scaffolds were developed successfully through a (CF/DMF) solvent system, obtaining a random fiber deposition that generated a porous structure with pore interconnectivity. However, with the solvent system used, it was not possible to generate fibers in the case of the neat PMMA sample. With the increase in the amount of PMMA in PLA/PMMA ratios, the fiber diameter of hybrid scaffolds decreases, and the defects (beads) in the fiber structure increase; these beads are associated with a nanoparticle agglomeration, that could be related to a low interaction between n-BG and the polymer matrix. The Young’s modulus of PLA/PMMA/n-BG decreases by 34 and 80%, indicating more flexible behavior compared to neat PLA. The PLA/PMMA/n-BG scaffolds showed a bioactive property related to the presence of hydroxyapatite crystals in the fiber surface after 28 days of immersion in a Simulated Body Fluids solution (SBF). In addition, the hydrolytic degradation process of PLA/PMMA/n-BG, analyzed after 35 days of immersion in a phosphate-buffered saline solution (PBS), was less than that of the pure PLA. The in vitro analysis using an HBOF-1.19 cell line indicated that the PLA/PMMA/n-BG scaffold showed good cell viability and was able to promote cell proliferation after 7 days. On the other hand, the in vivo biocompatibility evaluated via a subdermal model in BALC male mice corroborated the good behavior of the scaffolds in avoiding the generation of a cytotoxic effect and being able to enhance the healing process, suggesting that the materials are suitable for potential applications in tissue engineering.

Unexplained euploid embryo transfer failure (UEETF) is a frustrating and unanswered conundrum accounting for 30 to 50% of failures in in vitro fertilization using preimplantation genetic testing for aneuploidy (PGT-A). Endometriosis is thought by many to account for most of such losses and menstrual suppression or surgery prior to the next transfer has been reported to be beneficial. In this study, we performed endometrial biopsy in a subset of women with UEETF, testing for the oncogene BCL6 and the histone deacetylase SIRT1. We compared 205 PGT-A cycles outcomes and provide those results following treatment with GnRH agonist versus controls (no treatment). Based on these and previous promising results, we next performed a pilot randomized controlled trial comparing the orally active GnRH antagonist, elagolix, to oral contraceptive pill (OCP) suppression for 2 months before the next euploid embryo transfer, and monitored inflammation and miRNA expression in blood, before and after treatment. These studies support a role for endometriosis in UEETF and suggest that medical suppression of suspected disease with GnRH antagonist prior to the next transfer could improve success rates and address underlying inflammatory and epigenetic changes associated with UEETF.

The use of acellular nerve allografts (ANAs) to reconstruct long nerve gaps (>3 cm) is associated with limited axon regeneration. To understand why ANA length might limit regeneration, we focused on identifying differences in the regenerative and vascular microenvironment that develop within ANAs based on their length. A rat sciatic nerve gap model was repaired with either short (2 cm) or long (4 cm) ANAs, and histomorphometry was used to measure myelinated axon regeneration and blood vessel morphology at various timepoints (2-, 4- and 8-weeks). Both groups demonstrated robust axonal regeneration within the proximal graft region, which continued across the mid-distal graft of short ANAs as time progressed. By 8 weeks, long ANAs had limited regeneration across the ANA and into the distal nerve (98 vs. 7583 axons in short ANAs). Interestingly, blood vessels within the mid-distal graft of long ANAs underwent morphological changes characteristic of an inflammatory pathology by 8 weeks post surgery. Gene expression analysis revealed an increased expression of pro-inflammatory cytokines within the mid-distal graft region of long vs. short ANAs, which coincided with pathological changes in blood vessels. Our data show evidence of limited axonal regeneration and the development of a pro-inflammatory environment within long ANAs.

Ultra-small magnetic Fe3O4 nanoparticles are successfully synthesized in basic solutions by using the radiolytic method of the partial reduction in FeIII in the presence of poly-acrylate (PA), or by using the coprecipitation method of FeIII and FeII salts in the presence of PA. The optical, structural, and magnetic properties of the nanoparticles were examined using UV–Vis absorption spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and SQUID magnetization measurements. The HRTEM and XRD analysis confirmed the formation of ultra-small magnetite nanoparticles in a spinel structure, with a smaller size for radiation-induced particles coated by PA (5.2 nm) than for coprecipitated PA-coated nanoparticles (11 nm). From magnetization measurements, it is shown that the nanoparticles are superparamagnetic at room temperature. The magnetization saturation value Ms = 50.1 A m2 kg−1 of radiation-induced nanoparticles at 60 kGy is higher than Ms = 18.2 A m2 kg−1 for coprecipitated nanoparticles. Both values are compared with nanoparticles coated with other stabilizers in the literature.

A new curcuminoid molecule (3) has been designed and synthesized, containing a central -(CH2)2-COOH chain at the α carbon of the keto-enol moiety in the structure. The carboxylic acid group is added to react with exposed amino groups on silica oxide nanoparticles (nSiO2), forming an amide bond to attach the curcuminoid moiety to the nSiO2 covalently. The Kaiser test quantifies the functionalization degree, yielding 222 μmol of curcuminoid per gram of nanoparticles. The synthesized hybrid nanosystem, nSiO2-NHCO-CCM, displays significant emission properties, with a maximum emission at 538 nm in dichloromethane, similar to curcuminoid 1 (without the central chain), which emits at 565 nm in the same solvent. Solvent-induced spectral effects on the absorption and emission bands of the new hybrid nanosystem are confirmed, similar to those observed for the free curcuminoid (1). The new nanosystem is evaluated in the presence of kerosene in water, showing an emission band at 525 nm as a detection response. The ability of nSiO2-NHCO-CCM to change its fluorescence when interacting with kerosene in water is notable, as it overcomes the limitation caused by the insolubility of free curcuminoid 1 in water, allowing for the exploitation of its properties when connected to the water-stable nanosystem for future detection studies.

Administering exams in large enrollment courses is challenging and systems in place for accomplishing this task were upended in the spring of 2020 when a sudden transformation to online instruction and testing occurred due to the COVID-19 pandemic. In the following year, when courses remained online, approaches to improve exam security included measures like using test banks and reducing the allotted time for completing exams to reduce the sharing of information. A psychometric comparison using classical test theory of an unproctored online exam with one delivered in-person indicates both have comparable reliability. However, item-level analysis demonstrates some questions performed higher in the unproctored setting, with an important variable being the item's searchability online. Revising questions to increase generalizability and reduce searchability mitigate these performance differences. Further, changing the format for questions involving calculations from multiple-choice to open response with random number generation was found to increase difficulty and item discrimination and is a viable approach for improving exam security.

There is little doubt that motivation influences the extent to which individuals engage with online learning experiences. With the increasing role of digital technologies within chemistry higher education, this study illustrates how an augmented reality (AR)-supported educational escape activity (EEA), based on topics of inorganic stereochemistry, can be employed within an online environment. The design aspects of our activity were guided by principles of Self-Determination Theory (SDT)-an intrinsic-extrinsic theory of motivation. We sought to actively support the fundamental needs of competency, autonomy, and relatedness. Our control group was provided with a copy of our EEA that utilized two-dimensional drawings. Reported measures of competency were seen as a positive predictor of intrinsic motivation. However, in this study, this was not observed to be a positive predictor of academic performance. The introduction of AR, over and above the EEA, did not result in any significant differences in reported intrinsic motivation or post-test scores on our stereochemistry test instrument. Collected qualitative data suggest that participants found the activity to be useful and engaging. Through students' discussions, we have provided evidence of how design aspects of the EEA support the psychological needs satisfaction outlined by SDT. The design of our EEA provides one approach to implementing this style of learning activity, in a way that supports virtual presence and is scalable to large student cohorts.

The phytotoxicity of metals is established as a function of soil content; however, their potential negative effect is dependent on the type of soil and fundamentally on the presence of colloids in the soil, mainly of the organic type. For this reason, an experiment on the influence of Zn on the germination of Lepidium sativum L. in two acid soils with different organic matter contents was carried out. The results indicate that the potential phytotoxic effects of Zn at high levels are less pronounced in soils with high organic matter content compared to a soil with lower organic matter content. Therefore, it is of special interest to maintain adequate organic matter contents in agricultural soils in order to make them more sustainable and less vulnerable to potential contaminants. The experimental results obtained by students were highly satisfactory, showing experimental values similar to those previously found by the teachers. According to postlab surveys, the students were highly satisfied and in favor of the laboratory exercise developed from both sides, the didactic point of view and the importance of the exercise for the understanding of soil science concepts.

Vegetables cultivated close to highways have the potential to accumulate potentially toxic elements (PTEs), either through uptake from contaminated soil or via atmospheric deposition from vehicular emissions, and pose health risks when ingested by humans. The study investigated the concentrations of chromium (Cr), zinc (Zn), nickel (Ni), copper (Cu), cadmium (Cd), manganese (Mn), and iron (Fe) in lettuce (Lactuca sativa), African eggplant (Solanum melongena), and jute leaves (Corchorus olitorius) at distances 0–10, 50, and 200 m and the health risk of consuming these vegetables. Vegetable samples were digested using an automated digester, Behrotest model K8, and levels of potentially toxic elements were analyzed using an atomic absorption spectrophotometer (AAS) PinAAcle 900T. The mean element concentrations investigated in the three vegetables exceeded the WHO/FAO recommended limits except for Cu and Mn concentrations. The estimated mean concentrations of potentially toxic elements in the vegetables decreased with increasing distance from the edge of the road except for cadmium concentrations in African eggplant and chromium concentrations in jute leaves at 50 and 200 m distances. The estimated hazard index (HI) of potentially toxic elements in the vegetables in both children and adults was greater than 10 (HI > 10) and hence poses a possible health risk if ingested. The HI values for the various elements decreased with increasing distance from the edge of the road in lettuce and jute leaves, except for African eggplant, where the HI values increased with increasing distance from the edge of the road. Of the seven PTEs investigated, Cd, Cr, and Ni contributed the most to the overall HI in all the vegetables. It was further observed that the carcinogenic risk (CR) and total carcinogenic risk (TCR) for chromium and cadmium in the vegetables exceeded the threshold level of CR > 10−6 and TCR > 10−4 except for the cadmium value found in African eggplant at 200 m from the road. It is therefore recommended that the cultivation of vegetables along the highway should be halted as these vegetables pose potential health risks when consumed.

For the past five years, all Moroccan universities suspended practical work activities in the subject of chemistry for the first year due to a decision made by the Ministry of Higher Education. This study explores the effect of using a Microcomputer-Based Laboratory (MBL) on students' performance and investigates the desirability to convert first-year university-level practicals in chemistry from experimental demonstrations in lectures to the MBL. The study sample comprised 100 students attending the first year at the faculty of sciences of the Cadi Ayyad University (UCA) in Morocco. Students in the experimental group (N = 50) received a 1 h active engagement tutorial on acid-base titration using a microcomputer-based laboratory, in contrast to the control group (N = 50) who received the same instruction with a demonstration of the experiment. The experimental and control groups got randomly selected, and the same instructor trained both groups. The two groups of responders were compared based on their performance in a written exam that assesses the skills of processing, analyzing, and interpreting qualitative and quantitative experimental results of acid-base titration. As a result, the analysis of the obtained results showed that the experimental group performed significantly better in using appropriate mathematical skills for quantitative data analysis; and they were actively engaged in the acid-base titration experiment. The obtained results, together with similar findings from other studies, indicate the positive impact of using MBL on learning outcomes and support the adoption of the proposed learning environment in laboratory educational procedures as an alternative to traditional laboratories.