Structural basis for dual sedimentation of bacteriophage: Electron microscopy

Cirrhosis with ascites in the last year of life: a nationwide analysis of factors shaping costs, health-care use, and place of death in England

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMinimizing the Black Box Effect: Using Normal Mode Analysis to Integrate Computational Methods into the Physical Chemistry CourseJulio F. Caballero and Delphia F. Harris View Author Information Argentine Consultants in Education, 2306 Branard, Houston, TX 77098 Department of Chemistry and Physics, University of St. Thomas, 3800 Montrose Blvd, Houston, TX 77006Cite this: J. Chem. Educ. 1999, 76, 9, 1298Publication Date (Web):September 1, 1999Publication History Received3 August 2009Published online1 September 1999Published inissue 1 September 1999https://pubs.acs.org/doi/10.1021/ed076p1298https://doi.org/10.1021/ed076p1298research-articleACS PublicationsRequest reuse permissionsArticle Views204Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Molecular interactions,Molecules,Physical chemistry,Students Get e-Alerts

Provides suggestions for effectively integrating thermodynamics in the physical chemistry course.

We designed, implemented, and evaluated a game-based learning approach to increase student motivation and achievement for an undergraduate physical chemistry course. By focusing only on the most important game aspects, the implementation was realized with a production ratio of 1:8 (study load in hours divided by production effort in hours). Student motivation was found to increase significantly: compared to the traditional lecture format, self-study time was estimated to increase more than 3-fold to 4.6 h per week on average by the students. The failure rate in the final examination was also reduced, mainly because of bonus points that students could receive upon successful participation in the game. However, there is some indication that application of game-based learning might not improve higher-order thinking skills.

Solid-state nuclear magnetic resonance (NMR) spectroscopy finds growing application to inorganic and organic materials, biological samples, polymers, proteins, and cellular membranes. However, this technique is often neither included in laboratory curricula nor typically covered in undergraduate courses. On the other hand, spectroscopy and molecular structure taught in second-semester undergraduate physical chemistry courses meet the minimal background prerequisites for interpreting data obtained in many solid-state NMR experiments. A solid-state 2H NMR experiment is described in which the student obtains and interprets the spectrum of a powder sample of hexamethylbenzene-d18 using a solution NMR spectrometer as found in many undergraduate institutions. A quadrupolar-echo pulse sequence is applied to the sample to obtain the 2H NMR spectrum. The spectrum of a randomly oriented powder sample consists of two spectral branches with broad shoulders. The quadrupolar frequencies corresponding to the nuclear spin transitions are interpreted in terms of molecular mobility in the solid state, that is, 3-fold rotation of the methyl groups and 6-fold rotation of the hexamethylbenzene ring. In this way, students discover that solid substances may have significant molecular motions. This undergraduate investigation employing solid-state 2H NMR provides an informative exposure to state-of-the-art research techniques by using facilities that are already in place at many undergraduate institutions. Furthermore, it demonstrates a real-life manifestation of quantum mechanics as explained in physical chemistry courses, as well as fundamentals of molecular motions such as rotation of aromatic ring compounds and methyl groups in the solid state.

The COVID-19 pandemic has highlighted the importance of incorporating distance learning for long periods. However, few studies have addressed strategies to overcome the limitations caused by the lockdown. In this study, we report an active learning experience on the topic of chemical kinetics, using two flipped class approaches, team-based learning (TBL) and peer instruction (PI). These methodologies have been adapted to remote learning for undergraduate students from chemistry and engineering courses. Materials (video class and bibliography) were made available, as part of the preparation for the activities. TBL and PI groups performed the active learning activity (ALA), which consisted of graphic problems about kinetics of simple order reactions. An individual post-test was applied to assess the students' performance 2 weeks after ALA. In addition, students answered a questionnaire addressing their perceptions of ALA. The methodologies did not show significant differences in students' performances. Both enabled the acquisition of soft skills. Participants of both methodologies agree that traditional in-person classes could be partially or totally replaced by ALA, corresponding to 59.6% and 9.8%, respectively. PI participants presented a better perception of their learning than TBL students did. Thus, the use of technological tools in a recontextualized way, such as the adaptation of TBL and PI to a virtual environment, proved to be very promising for the Physical Chemistry course and an opportunity to implement a methodology that places students at the center of the teaching–learning process. The active learning activities proposed in this study can integrate distance learning, even after the pandemic context.

The identification of undergraduate chemistry students’ conceptual difficulties and common mistakes with basic concepts and problems in chemical kinetics provided the aim for this study, which involved 2nd-year/4th semester students who had passed the chemical kinetics component of a physical chemistry course. The study involved the analysis, evaluation and interpretation of students’ answers to the final examination in chemical kinetics. Three achievement groups, for the various topics, were identified: Group A, high achievement (mean ≈ 85%): (a) the steps in a chain-reaction mechanism, (b) integrated 1st- and 2nd-order rate laws; and (c) the Lindemann–Hinshelwood mechanism. Group B, intermediate achievement (mean ≈ 74%): (a) half-life, (b) instantaneous rate and the extent of reaction variable (ξ), (c) the Michaelis–Menten mechanism, and (d) theoretical rate law not asking for a final formula. Group C, low achievement (mean ≈ 54%): (a) experimental rate law and the reaction rate constant on the basis of an experimental-data table, (b) extracting the theoretical rate law, and (c) the Arrhenius equation. Students’ errors and misconceptions have also been identified. Successful students tended to respond well to straightforward questions on the theory of the subject, but had difficulties when solving problems. It is essential that teachers understand the potential of their students, especially possible misconceptions they may hold, and the teaching approaches that may contribute to overcoming the student difficulties. Problems in chemical kinetics can be very demanding both in terms of algebraic manipulations and conceptually. Teaching should focus on problem solving, with the emphasis on students themselves trying to solve the problems.

An experiment is presented in which the fluorescent lifetime versus pressure of excited I2 is studied. Variation in fluorescent lifetime when different quenching gases are added is also examined. A doubled Nd:YAG laser is used to excite fluorescence in iodine vapor. This pulsed 532 nm source is ideal for such measurements and the experiment is a nice complement to spectroscopic studies commonly done on iodine in undergraduate or graduate laboratory courses in physical chemistry or spectroscopy. Students acquire hands-on experience with lasers, vacuum manipulations, oscilloscopes, and computerized instrumentation. The emission intensity follows first-order decay kinetics and linear Stern–Volmer plots are obtained of rate constant versus pressure of quenching gas. Using gas kinetic theory, cross sections are deduced for quenching by He, Ne, Ar, Kr, H2, N2, O2, CO2, SF6, and I2 and values for 532 nm excitation are reported for the first time. Two theoretical models for the cross sections are examined and one...

There are several advantages to including polymer topics in both undergraduate and graduate physical chemistry courses. The first is to illustrate similarities and differences between systems with which the student is already familiar (such as ideal gases and metals) and more complex materials (in the present case polymeric materials having elastomeric properties). Another advantage is to provide particular examples illustrating the validity of very general results, such as the Carnot cycle analysis being independent of the working substance. It is possible to use aspects of rubberlike elasticity to illustrate a number of general molecular and thermodynamic concepts, making them more meaningful to the student. The items chosen here for this purpose are: (i) random flights of polymer chains and excluded volume effects, (ii) molecular origins of the elasticities of some types of materials, (iii) equations of state, (iv) thermodynamic non-ideality, (v) temperature changes during deformations and retractions, (vi) Carnot cycles and mechanochemistry, (vii) energy storage and hysteresis, and (viii) gel collapse.

The last year of life is often associated with a high level of healthcare utilisation and cost. To date, little information is available regarding the healthcare utilisation patterns in the last year of life in New Zealand. To describe the healthcare utilisation patterns and costs of the residents of Counties Manukau District Health Board (CMDHB) region in the 1-year period prior to death in 2008. CMDHB residents who died in 2008 were identified from the National Mortality Dataset. The health services utilisation patterns and costs in the last year of life were derived from National Minimum Dataset (NMDS), Pharmaceutical Collection, Laboratory Claims Collection, and National Non-Admitted Patient Collection via encrypted NHI linkage. Forty percent of all deaths in 2008 in CMDHB occurred in a publicly funded hospital. Just over 80% of people had at least one inpatient hospital stay in the last year of life. More than 75% of the healthcare costs funded by CMDHB in the last year of life were related to inpatient hospitalisations. The average cumulative length of inpatient stay over the year in the people who had an inpatient event was 20.6 days. Outpatient, pharmaceutical, and laboratory services were received by 84%, 91%, and 86% of people respectively in their last year of life. Consistent with the international literature, this study found that CMDHB residents in the last year of life have a high level of health service utilisation. Decisions about the appropriate use of high cost health services in people towards the end of life can be extremely challenging. These decisions are resource allocation decisions as well as clinical decisions and should be based on clinical factors, cost utilities, and patient, family, and society's expectations.

This study aimed to find out student and lecturer perceptions of students' learning difficulties and possible solutions proposed by them to these difficulties in physical chemistry. The data for this study were collected from 91 chemistry majors and two lecturers from two different chemistry education departments in two universities in Turkey. The findings suggest that student and lecturer perceptions of students' learning difficulties are quite different, as well as showing some common themes. The common themes were about the abstract nature of concepts in physical chemistry, the overloaded course content, insufficient resources, teacher-centered and exposition-dominated teaching practices and the lack of student motivation in the physical chemistry course. The discrepancies between student and lecturer perceptions were mostly marked by the student and faculty frustrations. Students were critical of the course content, the resources available, the lecturers, and their teaching methods. Lecturers generall...

On the basis of recent advances in battery research and technology, we have developed a novel laboratory exercise centered on an organic–inorganic battery using the redox chemistry of the organic molecule anthraquinone-2,7-disulfonic acid disodium salt (AQDS). Although most commercially available batteries are based on inorganic redox couples, the development of batteries based on organic redox active materials has great potential for stationary energy storage. As such, the experiment described in this report exposes students to state-of-the-art battery technology, despite a rather simple experimental protocol. The exercise allows students to acquire hands-on learning and visualize central concepts of the Nernst equation, battery technology and components, half-cell reactions, charging/discharging tests, and performance analysis. Additionally, students are required to operate a range of key electronic instruments, including multimeters, power supplies, and electronic loads. This laboratory exercise is part of a third semester undergraduate course in physical chemistry and can be completed in a single laboratory session. Student feedback shows that the experimental work, coupled with a written report, significantly broadens student understanding of the electrochemistry of batteries.

The third edition of this text has been completely rewritten and revised. It is intended for first- and second-year undergraduates in chemistry taking physical chemistry courses, and for undergraduates in other science and engineering subjects that require an understanding of chemistry. The author gives more attention to the solid and liquid states than is found in other texts on this subject, and introduces topics such as computer simulation and quasicrystals. Each chapter concludes with a set of problems, to which there are solution notes, designed to lead the reader to familiarity with the subject and its application in new situations. Computer programs designed to assist the reader are downloadable from the World Wide Web, from the time of publication. Detailed solutions to the problems will also be available via the World Wide Web. See http://www.cup.cam.ac.uk/stm/laddsolutions.htm. This modern text on physical chemistry will be of interest to undergraduate students in chemistry and also students in other areas of science and engineering requiring a familiarity with the subject.

This article presents a review of Physical Chemistry, 3rd edition by R. G. Mortimer. In its 1200 pages the author describes the most important topics in physical chemistry: thermodynamics and macroscopic description, dynamics (transport processes and chemical kinetics), quantum chemistry and spectroscopy, and statistical mechanics and thermodynamics. Other important information including tables of numeric data or mathematical hints necessary to understanding quantum calculations or solutions to proposed problems are also provided in extensive appendices. Each chapter can be studied as an independent section, but all can be also assembled as a whole. In brief, it is a good example of a textbook that has adapted well to the changes in progress in chemical education, and can be recommended to students in beginning physical chemistry courses.

Changes in attitudes towards chemical education and changes in physical chemistry itself invite a re-examination of the role of practical work in the teaching of physical chemistry. Several functions of laboratory work in physical chemistry are readily recognized. First, it gives opportunity for the student to acquire manipulative skills and secondly provides experience in making observations in a critical manner. At the same time the student may gain knowledge of a variety of experimental techniques. But besides these bench-skills practical work offers opportunity to develop other abilities in the student. The reporting and interpretation of results, and the presentation of scientific work can all be put in a realistic context for the student. Nor do the functions of practical work end here. After some experience the student may take a larger part in the design of experiments. Then there is the possibility of some investigational studies or a small research project to consider. All of these are widely recognized as important features to be considered in the design of courses in practical physical chemistry, but the relative importance of these various functions changes as physical chemistry itself develops. Considering a knowledge of techniques first it could be argued that there are some techniques (e.g. the use of vacuum lines) which are now so important in physical chemistry that every student should have some experience of them. On the other hand so many techniques are now employed in physical chemistry that an undergraduate course can cover only a fraction of them. Of the new instrumental techniques that are being introduced into chemistry we find increasingly that they are at the same time both more sophisticated and simpler. Very similar boxes with very similar knobs and meters replace different varieties of string and sealing wax. These developments have repercussions throughout chemistry. They change the position markedly in a physical chemistry teaching laboratory. Only twenty years ago the member of academic staff in charge of a physical chemistry laboratory could be familiar with the detailed construction of every piece of equipment, mechanical, electrical, optical or electronic. He could locate any fault that might arise and correct it. Frequently he expected students to develop the same attitude towards the instruments they used. But the introduction into the physical chemistry teaching laboratory of the mass spectrometer, the infra-red spectrometer, or even the packaged conductance bridge or direct-reading pH meter have changed all this. Indeed instrumentation is no longer confined to the physical laboratory. Increasingly, instrumental techniques are being employed in inorganic and organic teaching laboratories. It is likely in the