California Institute Of Technology Research Articles

Author Correction: A corridor of exposed ice-rich bedrock across Titan’s tropical region

In the version of this Article originally published, the author Rosaly Lopes was mistakenly affiliated with Northern Arizona University. Her affiliation has now been corrected to: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.

The Impact of Radiation Exposure upon Lithium-Ion Batteries for Future Planned NASA Missions to Europa

NASA is planning to launch a mission entitled the Europa Clipper which is intended to provide a detailed reconnaissance of the Jovian icy moon Europa. With one major objective being to determine the habitability of life on the moon, the mission will involve multiple flybys and will utilize a number of instruments, including an ice-penetrating radar that is intended to measure the thickness of the icy shell and possibly detect a subsurface ocean. As one would expect due to distances involved, the destination of Europa presents a number of technical challenges for the spacecraft, including being exposed to high levels of radiation and extreme temperature environments. Furthermore, NASA has stringent planetary protection protocols that must be followed that involves sterilizing the spacecraft to to avoid any potential contamination. As described previously1,2, the current power subsystem architecture for the Europa Clipper mission involves the use of solar arrays, power management electronics, and a rechargeable lithium-ion battery.3 With respect to the Li-ion battery, we are planning to utilize a “small cell” approach, which will consist of multiple high specific energy small 18650-size Li-ion cells that are assembled into large capacity multi-string batteries. Due to the excellent cell-to-cell reproducibility and proper cell matching, individual cell monitoring and balancing circuitry is not required with this approach. NASA has previously utilized this approach on a number of past missions, including Kepler, Aquarius, and SMAP. To meet the challenging mission requirements, we identified leading candidate cell chemistries that are projected to meet the mission requirements. However, in contrast to these previous missions which have utilized heritage Sony HCM 18650 cells, we are planning on using much higher specific energy cells to reduce the overall spacecraft mass. Given that we would like to use a new cell chemistry, it necessitates performing a cell qualification activity. Furthermore, the candidate cell chemistry must be demonstrated to have good cycle and storage life characteristics, especially since the cruise period to Europa is extremely long and could potentially be over 6.5 years in duration, depending upon the launch vehicle selected. To reduce the bio-burden of spacecraft components, dry heat microbial reduction (DHMR) is typically employed, which involves subjecting the samples to exposure at high temperatures (in excess of 150oC). However, since Li-ion cell technology will rapidly degrade at high temperatures, this methodology is not acceptable and alternative methods of achieving sterility must be adopted. The preferred method with respect to the Li-ion batteries is to subject them to high levels of gamma-irradiation, which has previously been demonstrated to have a minimal to low impact upon the performance characteristics.4,5 To assess the impact that would be sustained by exposure to γ-rays prior to launch to comply with planetary protection protocols, as well as to address the radiation exposure during the course of the mission, we have exposed a number of Li-ion cells and a large capacity battery module to gamma-irradiation (60Co source) at very high levels (up to 20 Mrad) to evaluate the potential impact. In order to demonstrate the impact of irradiation, a number of performance characterization tests were implemented on samples subjected to varying levels of γ-rays (either 12 Mrad or 20 Mrad), including: (i) 100% DOD cycling under various conditions, (ii) charge and discharge rate characterization over a range of temperatures, (iii) module level testing and, (vi) verification of proper functionality of internal safety protection devices. As will be discussed, good performance has been obtained with candidate high specific energy Li-ion cells, and minimal capacity loss was observed after being subjected to high levels of radiation. ACKNOWLEDGEMENT The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA) and supported by the Europa Clipper Mission. A. Ulloa-Severino, G. A. Carr, D. J. Clark, S. M. Orellana, R. Arellano, M.C. Smart, B.V. Ratnakumar, A. Boca, and S. F. Dawson. October 5, 2016. F. C. Krause, A. Lawrence, M. C. Smart, S. F. Dawson, A. Ulloa-Severino, and B. V. Ratnakumar, 227th ECS Meeting, May 28, 2015. M. C. Smart, F. C. Krause, A. Lawrence, B. V. Ratnakumar, A. Ulloa-Severino, and R. C. Ewell, 232th ECS Meeting, October 5, 2017. B. V. Ratnakumar, M. C. Smart, L. D. Whitcanack, E. D. Davies, and K. B. Chin, J. Electrochem. Soc., 151 (4), A652- A659 (2004). B. V. Ratnakumar, M. C. Smart, L. D. Whitcanack, E. D. Davies, K. B. Chin, F. Deligiannis, and S. Surampudi, J. Electrochem. Soc., 152 (2), A357- A363 (2005).

Gift of Sight: Stem-Cell Patches for Wet and Dry Macular Degeneration.

Regenerative Patch Technologies LLC was founded by Mark Humayun, MD, PhD, and David R. Hinton, MD, from the University of Southern California; and Dennis O. Clegg, PhD, from the University of California, Santa Barbara. The technology to produce the stem cell-based retinal implant is exclusively licensed to Regenerative Patch Technologies LLC from the University of Southern California, the California Institute of Technology, and the University of California, Santa Barbara. Humayun and Hinton have an equity interest in and are consultants for Regenerative Patch Technologies LLC.

How Much Will Gallium Oxide Power Electronics Cost?

Samantha Bench Reese is a senior engineer at the Strategic Energy Analysis Center at National Renewable Energy Laboratory (NREL). As an analyst, Samantha helps put early-stage research problems in context of technoeconomic tradeoffs and analytically shows technology potential through supply-chain analysis, trade-flow mapping, market research, and building bottom-up cost models. Prior to joining NREL, she helped transition products from R&D to volume manufacturing. Samantha's background is in mechanical and electrical engineering. She received an M.S. in Engineering and Applied Science from Yale University and a B.S. in Engineering and Applied Science from California Institute of Technology (Caltech). Timothy Remo is a manufacturing analyst in the Techno-Economic Analysis Group in the Strategic Energy Analysis Center at NREL. Tim’s areas of expertise include cost analysis of semiconductor manufacturing, process development and process optimization, and design of experiments. His research interests include cost-competitive renewable energy alternatives, economics of changing energy costs and demand, and challenges associated with smarter grid technology. Prior to joining NREL, Tim was a process and product engineer in the semiconductor and photovoltaics industry. Tim received his B.S. in Mechanical Engineering from University of South Florida and B.A. in Physics from University of Florida. Johney Green Jr. is an Associate Laboratory Director for Mechanical and Thermal Engineering Sciences (MTES) at NREL. He oversees NREL's transportation, buildings, wind, water, geothermal, advanced manufacturing, and concentrating solar power research programs. Prior to joining NREL, Johney held a number of leadership roles at Oak Ridge National Laboratory (ORNL), served as technical coordinator at the U.S. Department of Energy, and worked with Ford Motor Company. Green has received several awards during his career and served on numerous advisory boards. Dr. Green received his Mechanical Engineering degrees from Georgia Institute of Technology (Ph.D., M.S.) and The University of Memphis (B.S.). Andriy Zakutayev is a scientist at Materials Science Center at NREL, leading a team working on new materials for advanced energy technologies. His research interests include discovery and development of materials for solar cells, Li-ion batteries, fuel cells, power electronics, and other renewable energy technologies. Andriy is an author of more than 100 peer-reviewed publications and a reviewer for more than 50 scientific journals. He has received an EMRS Young Scientist Award along with many other professional recognitions. Dr. Zakutayev received his Ph.D. in Physics from Oregon State University and B.S. in Electronics from Lviv Polytechnic National University (Ukraine).

Navigation: from animal behaviour to guiding principles

![Figure][1] Tritonia diomedea navigating through a sea pen bed in search of prey or mates. Photo credit: Russell Wyeth and James A. Murray. Whether an animal's world is restricted to a few twigs or the avian highways that traverse the planet, creatures must navigate their surroundings

Lithium Plating–a Life-Limiting and Safety Issue in a Li-Ion Cell

Despite their advances and widespread use in various applications for the last two decades, Li-ion batteries continue to exhibit occasional failures from Li plating on the anode. Li plating can have immediate effects on performance and more devastating effects upon the safety, if the Li plating occurs in a dendritic form that could pierce through the separator causing an internal short. Even in a benign form, plated Li—lacking the protective SEI that protects the carbon anode —tends to react with electrolyte which results in a rapid growth in interfacial impedance and capacity loss during cycling. Li plating will manifest whenever intercalation kinetics (into carbon) are slower compared to lithium plating over carbon, despite the lower reversible potential of the latter. Poor cell design factors, i.e., improper matching of anode and cathode in terms of electrochemical capacities and geometric aspects with localized hotspots in current distribution, and inappropriate electrolyte, can cause Li plating on the anode. The nature of the anode, electrolyte and SEI are among the most important factors that can influence Li plating.1 Apart from the design/chemical abnormalities, lithium plating is also triggered by the operational conditions, such as fast charge rates and low operating temperatures relevant to planetary space missions. In our earlier study, we have demonstrated that the choice of the electrolyte is critical in determining the propensity towards lithium plating.2 Specifically, these studies indicate that the Li intercalation kinetics are mainly dictated by the anode surface films (SEI), which in turn could be controlled by a judicious selection of electrolyte solution, i.e., both solvent and salt. We have established a correlation between the poor lithium intercalation kinetics and the propensity towards lithium plating using different electrolytes with different solvent blends and different electrolyte additives. Recently, Li plating was observed in cells upon extended cycling at ambient temperature in a Low Earth Orbit (LEO) satellite simulation condition, involving 30 minutes of discharge and 60 minutes of charge continuously, possibly due to impeded intercalation kinetics at the anode. Likewise, exposure to high intensity radiation environments may have led to Li plating in prototype 18650 cells upon subsequent cycling. In this paper, we will discuss the Li plating phenomenon in these specific examples, and with reference to anode/cathode interfacial kinetics at low temperatures in different electrolytes. ACKNOWLEDGEMENT The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). REFERENCES B. V. Ratnakumar and M. C. Smart, ECS Trans. 25 (36), 241 (2010).M. C. Smart and B. V. Ratnakumar, J. Electrochem. Soc. 2011, 158 (4), A379.

ACM SIGMETRICS International Workshop on Critical Infrastructure Network Security

The second ACM SIGMETRICS International Workshop on Critical Infrastructure Network Security took place in Irvine, California, USA on June 18th 2018 in conjunction with ACM SIGMETRICS 2018. As in the previous year, the workshop received widespread community support and as a consequence we were able to conduct a successful workshop. The workshop provided a forum for scientists and engineers from research institutions and universities to present their findings on critical infrastructure security. It also provided a forum for an exchange of ideas and in-depth discussions on the future research directions in this area. The workshop featured several invited and contributed talks from researchers from institutions such as the University of Illinois at Urbana-Champaign, Princeton University, Sandia National Laboratories, Delft University (The Netherlands), ENEA (Italy), Northeastern University, Hamburg University (Germany), National University of Singapore, California Institute of Technology, New York University and University of Kentucky. To disseminate the outcome of this workshop, we are pleased to include extended abstracts of selected workshop presentations in Performance Evaluation Review (PER), the quarterly publication of ACM SIGMETRICS. A brief overview of the included papers is outlined below.

A Bibliometric Profile of the Remote Sensing Open Access Journal Published by MDPI between 2009 and 2018

Remote Sensing Open Access Journal (RS OAJ) is an international leading journal in the field of remote sensing science and technology. It was first published in the year 2009 and is currently celebrating tenth year of publications. In this research, a bibliometric analysis of RS OAJ was conducted based on 5588 articles published during the 10-year (2009–2018) time-period. The bibliometric analysis includes a comprehensive set of indicators such as dynamics and trends of publications, journal impact factor, total cites, eigenfactor score, normalized eigenfactor, CiteScore, h-index, h-classic publications, most productive countries (or territories) and institutions, co-authorship collaboration about countries (territories), research themes, citation impact of co-occurrences keywords, intellectual structure, and knowledge commutation. We found that publications of RS OAJ presented an exponential growth in the past ten years. From 2010 to 2017 (for which complete years data were available), the h-index of RS OAJ is 67. From 2009–2018, RS OAJ includes publications from 129 countries (or territories) and 3826 institutions. The leading nations contributing articles, based on 2009–2018 data, and listed based on ranking were: China, United States, Germany, Italy, France, Spain, Canada, England, Australia, Netherlands, Japan, Switzerland and Austria. The leading institutions, also for the same period and listed based on ranking were: Chinese Academy of Sciences, Wuhan University, University of Chinese Academy of Sciences, Beijing Normal University, The university of Maryland, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, China University of Geosciences, United States Geological Survey, German Aerospace Centre, University of Twente, and California Institute of Technology. For the year 2017, RS OAJ had an impressive journal impact factor of 3.4060, a CiteScore of 4.03, eigenfactor score of 0.0342, and normalized eigenfactor score of 3.99. In addition, based on 2009–2018, data co-word analysis determined that “remote sensing”, “MODIS”, “Landsat”, “LiDAR” and “NDVI” are the high-frequency of author keywords co-occurrence in RS OAJ. The main themes of RS OAJ are multi-spectral and hyperspectral remote sensing, LiDAR scanning and forestry remote sensing monitoring, MODIS and LAI data applications, Remote sensing applications and Synthetic Aperture Radar (SAR). Through author keywords citation impact analysis, we find the most influential keyword is Unmanned Aerial Vehicle (UAV), followed, forestry, Normalized Difference Vegetation Index (NDVI), terrestrial laser scanning, airborne laser scanning, forestry inventory, urban heat island, monitoring, agriculture, and laser scanning. By analyzing the intellectual structure of RS OAJ, we identify the main reference publications and find that the themes are about Random Forests, MODIS vegetation indices and image analysis, etc. RS OAJ ranks first in cited journals and third in citing, this indicates that RS OAJ has the internal knowledge flow. Our results will bring more benefits to scholars, researchers and graduate students, who hopes to get a quick overview of the RS OAJ. And this article will also be the starting point for communication between scholars and practitioners. Finally, this paper proposed a nuanced h-index (nh-index) to measure productivity and intellectual contribution of authors by considering h-index based on whether the one is first, second, third, or nth author. This nuanced approach to determining h-index of authors is powerful indicator of an academician’s productivity and intellectual contribution.

What we can learn from safety experts in other fields

Nearly every chemist has some connection to a major safety incident. For me, I started graduate school at the California Institute of Technology a year after graduate student Ramsay Bittar was severely injured when a flask overpressurized and exploded during a synthesis procedure and a shard of glass severed an artery in his neck. Years later, a colleague in the field of bioinorganic chemistry, Dartmouth College professor Karen Wetterhahn, died of mercury poisoning after exposure to dimethylmercury in her lab. Her group was working on science close to mine, and I talked with her students about how to finish their research after her death. My connection to Sheri Sangji came when the National Academies of Sciences, Engineering, and Medicine asked me to chair a committee that would prepare a new report on chemical safety. The study was commissioned partly in response to Sangji’s death, and the academies had a novel

I thought it would never happen to me

“Don’t worry, that would never happen to me” was a common refrain I used with friends and family in the wake of Sheri Sangji’s death. Although the Sangji case rightfully sparked much-needed discussion and action on academic laboratory safety at the national level, in many cases we were (are) much slower to embrace change as individuals. This was certainly the case for me. When she died, I was a third-year graduate student. I’d been working with pyrophorics for several years. I was young and felt invincible. It was difficult to comprehend the potential severe consequences of a lab accident. As a result, Sangji’s death was for me not an instant paradigm shift but rather the start of a gradual awakening to the importance of laboratory safety. In my graduate lab at the California Institute of Technology, one of the most noticeable and important changes after Sangji’s death was that we,

La- and La-/Ce-Doped BaF2 Crystals for Future HEP Experiments at the Energy and Intensity Frontiers Part I

In addition to La-doped barium fluoride (BaF2) crystals, La/Ce co-doped BaF2 crystals were also investigated at the California Institute of Technology, Pasadena, CA, USA. Strong cerium-induced emissions peaked at 305 and 320 nm with a decay time of 25 ns were observed, in addition to the fast and slow scintillation at 220 and 300 nm, respectively. The La/Ce co-doping was also found effective in suppressing the slow component in BaF2. Compared to La-doped crystals, the La/Ce co-doped crystals have a better light output in both 50- and 2500-ns gate. The fast/slow ratio of La/Ce co-doped crystal was found to be about 1/1, similar to La-doping, which is also considered not sufficient for pile-up suppression. A 20-cm-long La/Ce co-doped BaF2 crystal shows also excellent optical quality and light response uniformity.

Challenges in the development and verification of first-principles models in Hall-effect thruster simulations that are based on anomalous resistivity and generalized Ohm’s law**© 2018. California Institute of Technology. Government sponsorship acknowledged.

Since the inception of the Hall-effect thruster more than five decades ago, many theories have been proposed about the source(s) of the anomalous cross-field transport that is known to occur in these devices. Yet, none of these theories has been implemented in two-dimensional (2D) (r–z) simulations and successfully predicted the behavior of the discharge and the erosion of a thruster over different operating conditions and geometries. We present results from numerical experiments with a 2D (r–z) axisymmetric hydrodynamics code that show the plasma solution is relatively insensitive to very large variations in the anomalous transport in some regions of the discharge channel and near-plume. Because the changes of the plasma properties in these regions can be too small or impossible to detect in the laboratory by conventional diagnostics, the verification of a transport model becomes very challenging. Hence, without more advanced diagnostics and improved numerical models, comparisons between plasma measurements and simulation results can lead to wide-ranging theories and scalings of the anomalous resistivity.

La- and La-/Ce-Doped BaF2 Crystals for Future HEP Experiments at the Energy and Intensity Frontiers Part II

In addition to La-doped barium fluoride (BaF2) crystals, La/Ce co-doped BaF2 crystals were also investigated at the California Institute of Technology, Pasadena, CA, USA. Strong cerium-induced emissions peaked at 305 and 320 nm with a decay time of 25 ns were observed, in addition to the fast and slow scintillation at 220 and 300 nm, respectively. The La/Ce co-doping was also found effective in suppressing the slow component in BaF2. Compared to La-doped crystals, the La/Ce co-doped crystals have a better light output in both 50- and 2500-ns gate. The fast/slow ratio of La/Ce co-doped crystal was found to be about 1/1, similar to La-doping, which is also considered not sufficient for pile-up suppression. A 20-cm-long La/Ce co-doped BaF2 crystal shows also excellent optical quality and light response uniformity.

Nobel Prize in Chemistry – 2018

The 2018 Nobel Prize for Chemistry rewards research on the use of bacteria and viruses to generate and screen highly diverse protein sequences for improved catalytic and ligandbinding function. One half of the Prize was awarded to Professor Frances Arnold of the California Institute of Technology (California, USA). The other half was awarded jointly to Professor George P Smith of the University of Missouri (Columbia, USA) and Professor Sir Gregory P Winter of the Medical Research Council’s Laboratory of Molecular Biology (Cambridge, UK). The three winners have been amongst the tallest of stalwarts in combinatorial approaches to protein engineering.

Cluster Preface: Synthesis of Materials

Timothy M. Swager is the John D. MacArthur Professor of Chemistry and the Director, Deshpande Center for Technological Innovation at the Massachusetts Institute of Technology. A native of Montana, he received a BS from Montana State University in 1983 and a Ph.D. from the California Institute of Technology in 1988. After a postdoctoral appointment at MIT he was on the chemistry faculty at the University of ­Pennsylvania and returned to MIT in 1996 as a Professor of Chemistry and served as the Head of Chemistry from 2005 to 2010. He has published more than 450+ peer-reviewed papers and more than 90+ ­issued/pending patents. Swager’s honors include: Election to the ­National Academy of Sciences, an Honorary Doctorate from Montana State University, the ­Linus Pauling Medal, the Lemelson-MIT Award for Invention and Innovation, Election to the American Academy of Arts and Sciences, The American Chemical Society Award for Creative Invention, and The Carl S. Marvel Creative Polymer Chemistry Award (ACS). Swager’s research interests are in design, synthesis, and study of organic-based electronic, sensory, high-strength, liquid crystalline, and colloid materials. His inventions have had wide-ranging commercial impact, including the ­FidoTM sensors, which are the world’s most sensitive explosives detectors. He is the scientific founder of five companies (­DyNuPol, Iptyx, PolyJoule, C2 Sense, and Xibus Systems) and has served on ­numerous corporate and government boards.

C&EN talks with Frances Arnold, newly minted Nobel laureate

From all appearances, Frances H. Arnold has mastered the art of travel. Seemingly impervious to jet lag, she was a patient and polished subject when C&EN interviewed her in Boston on a Wednesday morning in October, precisely two weeks after the announcement that she won the 2018 Nobel Prize in Chemistry. The day before, she’d been in Albany, and the day before that she’d been on the Hawaiian island of Oahu. These were all trips she planned before learning she won the Nobel—an accolade that tends to boost its recipients’ opportunities to travel by an order of magnitude. “Life is a tornado, and I am a leaf,” Arnold says. As the Linus Pauling Professor of Chemical Engineering, Bioengineering & Biochemistry at California Institute of Technology, Arnold’s schedule was already packed. Now she’s trying to figure out how to juggle her teaching responsibilities and the lectures she promised to give with

Elie Wollman and the question of lysogeny

The rise of Molecular Biology occurred in part via the spectacular convergence of few schools of thoughts located on each side of the Atlantic Ocean. This paper underlines the importance of the personal trajectory followed by Elie Wollman, as a shuttle between the Institut Pasteur and the Division of Biology of the California Institute of Technology in the elucidation of the phenomena of lysogeny.

How to Measure Thermoelectric Properties Reliably

Tian-Ran Wei is currently an assistant professor at the School of Materials Science and Engineering, Shanghai Jiao Tong University. He obtained his PhD from Tsinghua University in 2017. He worked at Shanghai Institute of Ceramics, Chinese Academy of Sciences from 2017 to 2018 before joining Shanghai Jiao Tong University. His current research focuses on advanced thermoelectric materials. Mengjia Guan is a PhD student at the Shanghai Institute of Ceramics, Chinese Academy of Sciences. She obtained her BS from Central South University in 2014. Her research focuses on superionic copper chalcogenide thermoelectric materials. Junjie Yu is a PhD student at the School of Materials Science and Engineering, Zhejiang University. He obtained his BS from Zhejiang University in 2015. His research focuses on half-Heusler thermoelectric materials. Tiejun Zhu is the Qiushi Distinguished Professor of Materials Science and Engineering at Zhejiang University. He obtained his PhD from Zhejiang University in 2001. He was a research fellow at Singapore-MIT Alliance from 2002 to 2004, and a visiting scientist at California Institute of Technology in 2011. He has been a faculty member at Zhejiang University since 2004. His current research focuses on the advanced fabrication, microstructure, and transport mechanisms of high-efficiency thermoelectric materials. Lidong Chen is a Professor of Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), and the Co-Editor-in-Chief of npj Computational Materials. He received his BS (1982) from Hunan University and doctorate (1990) from Tohoku University. After being chief engineer and postdoctoral appointment at Riken Cooperation and Japan National Aerospace Laboratory, respectively, he worked at the Institute for Materials Research, Tohoku University, as research associate and associate professor. He joined SICCAS as a professor in 2001. His research mainly focuses on the design, synthesis, and characterization of thermoelectric materials and devices. Xun Shi is a professor at the School of Materials Science and Engineering, Shanghai Jiao Tong University. He received his BS (2000) in Tsinghua University and PhD (2005) in the University of Chinese Academy of Sciences. He worked at the University of Michigan (USA) as a postdoc from 2007 to 2009. He then joined the R&D center in General Motors. Since 2010 he has been a professor at the Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS). His current research focuses on advanced thermoelectric materials and flexible semiconductors.

Mapping the use of open access resources by doctoral students in the USA by employing citation analysis

PurposeThe purpose of this paper is to measure the fully open access (OA) contents cited by researchers from top three universities in the USA (MIT, CIT and Stanford) in the field of physics. This study aims to identify the core fully OA journals widely used by researchers in the field of physics and evaluate the cited fully OA resources by applying various scientometric parameters to check the credibility of these OA resources.Design/methodology/approachThe PhD theses awarded during 2014 in the field of physics and hosted in the institutional repositories of Massachusetts Institute of Technology (MIT), California Institute of Technology (CIT) and Stanford University, respectively, were selected and scanned to extract references of sources cited. Later on, Google Scholar was used to identify source journals of the extracted references. Only source “journals” were selected and analyzed; rest of other sources were ignored; accordingly, toll-access and OA journals were segregated, as such the OA-cited journals could be identified. The scientometric performance indicators were used to check the quality of identified core fully OA journal cited by USA researchers in the field of physics.FindingsThe results of this study show that fully OA resources are sufficiently used by the researchers of top three academic institutions of the world/USA. The study was also successful in identifying the core fully OA journals; besides it also reveals that these fully OA journals are highly impressive as showed by performance indicators applied. The major finding of the research includes the identification of top ten fully OA journals along with their impact based on different scientometric parameters like number of times cited, impact factor, h-index, immediacy index, impact per publication and Scimago Journal Rank (SJR).Research limitations/implicationsBecause of a limited corpus of literature scrutinized in this study, the findings of the study may or may not represent the global picture in the field of physics.Practical implicationsThe paper confirms that fully OA resources usage trend is positively increasing day by day, and there are vast numbers of core OA journals with high-quality impact available for use to researchers around the world. Besides, the paper also affirms the view that there should be more publicity of fully OA literature around the globe to reap the benefits of the same.Social implicationsThis paper will assist researchers, libraries, information centers and research and development institutions to take a cost-efficient approach in using and disseminating the scholarly literature.Originality/valueThis paper is one of the first pieces of research conducted on electronic theses and dissertation (ETD’s) in top three universities of the USA, to check usage percentage and quality of fully OA journal resources cited by doctoral students in the field of physics.

Reactions

OPINION Reactions ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2018, 96 (40), p 3October 8, 2018Cite this:C&EN 96, 40, 3(Credit: Will Ludwig/C&EN/Shutterstock)Figure1of1▸ Letters to the editor Graduate student journeys The “Chemistry Grad School Experience” issue (C&EN, Sept. 10, page 16) spent most of its time on negative aspects of a Ph.D. program. But that is not how I remember it.Getting a chemistry Ph.D. can be a wonderful experience and a special time that is unlikely to be repeated in any career. Once you get past whatever coursework and exams are required, there is an extended period where all you really have to do is research. You have no other obligations—no meetings, no schedule, no one monitoring your working hours. Just come in and do experiments, calculations, whatever, until you are too tired to go on; sleep, wake up when you want to, and do some more research.It is also a time of being in a close community—your own research group and all the other chemistry graduate students. If you are lucky, as I was, you also develop a very close relationship with your thesis adviser and possibly with other faculty, and you begin to become a part of the larger community of your area of research through attending meetings, meeting visiting scientists, and listening to seminars.I wish that the issue, which had much good advice, had done a bit more to capture the pleasure and privilege of getting a Ph.D. in chemistry.Bernard J. Bulkin London I am writing in response to the article by Mitch Jacoby in the Sept. 10 issue (page 20). I was a young assistant professor at the University of Wisconsin, Eau Claire, in 1966 when my research assistant applied to four graduate schools in chemistry: Harvard University, Massachusetts Institute of Technology, California Institute of Technology, and the University of California, Berkeley. He received offers from all four! He asked which one I would recommend, and my comment was they are all excellent. The next day he told me that he would attend Caltech. I asked, Why? He had been watching a popular TV show called “The Man From U.N.C.L.E.,” and it had filmed scenes in labs at Caltech. That convinced him! He earned his Ph.D. under professor Harry Gray in 1971 and never left. George Rossman is now a professor of mineralogy and is a world authority on gemstones. My former student is now a “rock star”! Allen A. Denio Newark, Del. Correction Sept. 3, page 8: The news story about an 18-electron alkaline earth metal complex incorrectly describes a spectroscopic shift as being to a lower wavelength. The shift was to a longer wavelength.