Fuel cell applications for novel metalloporphyrin catalysts

This project utilized Computer-Aided Molecular Design (CAMD) to develop a new class of metalloporphyrin materials for use as catalysts for two fuel cell reactions. The first reaction is the reduction of oxygen at the fuel cell cathode, and this reaction was the main focus of the research. The second reaction we attempted to catalyze was the oxidation of methanol at the anode. Two classes of novel metalloporphyrins were developed. The first class comprised the dodecaphenylporphyrins whose steric bulk forces them into a non-planar geometry having a pocket where oxygen or methanol is more tightly bound to the porphyrin than it is in the case of planar porphyrins. Significant improvements in the catalytic reduction of oxygen by the dodecaphenyl porphyrins were measured in electrochemical cells. The dodecaphenylporphyrins were further modified by fluorinating the peripheral phenyl groups to varying degrees. The fluorination strongly affected their redox potential, but no effect on their catalytic activity towards oxygen was observed. The second class of porphyrin catalysts was a series of hydrogen-bonding porphyrins whose interaction with oxygen is enhanced. Enhancements in the interaction of oxygen with the porphyrins having hydrogen bonding groups were observed spectroscopically. Computer modeling was performed using Molecular Simulations new CERIUS2 Version 1.6 and a research version of POLYGRAF from Bill Goddard`s research group at the California Institute of Technology. We reoptimized the force field because of an error that was in POLYGRAF and corrected a problem in treatment of the metal in early versions of the program. This improved force field was reported in a J. Am. Chem. Soc. manuscript. Experimental measurements made on the newly developed catalysts included the electrochemical testing in a fuel cell configuration and spectroscopic measurements (UV-Vis, Raman and XPS) to characterize the catalysts

Optical and EPR spectroscopy of Er3+ in lithium yttrium borate, Li6Y(BO3)3:Er single crystals

The energy levels of Er3+ ions have been determined in lithium yttrium borate (Li6Y(BO3)3) single crystals in a wide spectral range between 6000 and 40000 cm-1 together with an analysis of the ground state, using optical and EPR spectroscopy. The crystal field splittings of the 4I15/2 ground state and those of nearly all excited states up to the 4D7/2 manifold have been obtained at low temperature from luminescence (T = 5 K) and absorption (T = 9 K) measurements, respectively. The numbers of experimentally observed Stark sublevels agree well with those expected theoretically for Er3+ ions occupying a single low symmetry (C1) site. A full set of g- and 167Er hyperfine tensor parameters are presented for the ground state characterized by EPR; the measured Orbach-type spin-relaxation rates viz. the involved activation energies correspond to the optically derived lowest excited sublevels

Effect of symmetry reduction on the electronic transitions in polytypic GdAl3(BO3)4:Eu:Tb crystals

The existence of a recently described monoclinic phase (C2/c, Z=8) in addition to the well-known Huntite type rhombohedral (R32) polytypic modification of the GdAl3(BO3)4 (GAB) crystal at room temperature provides a unique possibility to investigate the incorporation of rare earth dopants into slightly modified crystal lattice by spectroscopic methods. In these characteristic GAB structures the dopant ions, e.g Tb3+ or Eu3+ , possess slightly different neighbor geometries and local symmetries. The Tb3+:7F6 → 5D4 and Eu3+:7F0,1,2 → 5D0,1,2 electronic transitions were successfully identified in the absorption spectra using polarization, concentration and temperature dependent measurements in both polytypic modifications. The positions of the investigated Tb lines are shifted by up to 10 cm−1 due to symmetry changes. In addition, some of the Eu lines show splittings of about 4–30 cm−1 as a consequence of the change of the local environment. From the room temperature absorption measurements some of the low energy crystal field levels of 7F and 5D states of the Eu3+ ions were successfully determined for both modifications

Gravitational wave astronomy of single sources with a pulsar timing array

Abbreviated: We investigate the potential of detecting the gravitational wave from individual binary black hole systems using pulsar timing arrays (PTAs) and calculate the accuracy for determining the GW properties. This is done in a consistent analysis, which at the same time accounts for the measurement of the pulsar distances via the timing parallax. We find that, at low redshift, a PTA is able to detect the nano-Hertz GW from super massive black hole binary systems with masses of \sim10^8 - 10^{10}\,M_{\sun} less than $\sim10^5$\,years before the final merger, and those with less than $\sim10^3 - 10^4$ years before merger may allow us to detect the evolution of binaries. We derive an analytical expression to describe the accuracy of a pulsar distance measurement via timing parallax. We consider five years of bi-weekly observations at a precision of 15\,ns for close-by ($\sim 0.5 - 1$\,kpc) pulsars. Timing twenty pulsars would allow us to detect a GW source with an amplitude larger than $5\times 10^{-17}$. We calculate the corresponding GW and binary orbital parameters and their measurement precision. The accuracy of measuring the binary orbital inclination angle, the sky position, and the GW frequency are calculated as functions of the GW amplitude. We note that the "pulsar term", which is commonly regarded as noise, is essential for obtaining an accurate measurement for the GW source location. We also show that utilizing the information encoded in the GW signal passing the Earth also increases the accuracy of pulsar distance measurements. If the gravitational wave is strong enough, one can achieve sub-parsec distance measurements for nearby pulsars with distance less than $\sim 0.5 - 1$\,kpc.Comment: 16 pages, 5 figure,, accepted by MNRA

Replication Timing: A Fingerprint for Cell Identity and Pluripotency

Many types of epigenetic profiling have been used to classify stem cells, stages of cellular differentiation, and cancer subtypes. Existing methods focus on local chromatin features such as DNA methylation and histone modifications that require extensive analysis for genome-wide coverage. Replication timing has emerged as a highly stable cell type-specific epigenetic feature that is regulated at the megabase-level and is easily and comprehensively analyzed genome-wide. Here, we describe a cell classification method using 67 individual replication profiles from 34 mouse and human cell lines and stem cell-derived tissues, including new data for mesendoderm, definitive endoderm, mesoderm and smooth muscle. Using a Monte-Carlo approach for selecting features of replication profiles conserved in each cell type, we identify “replication timing fingerprints” unique to each cell type and apply a k nearest neighbor approach to predict known and unknown cell types. Our method correctly classifies 67/67 independent replication-timing profiles, including those derived from closely related intermediate stages. We also apply this method to derive fingerprints for pluripotency in human and mouse cells. Interestingly, the mouse pluripotency fingerprint overlaps almost completely with previously identified genomic segments that switch from early to late replication as pluripotency is lost. Thereafter, replication timing and transcription within these regions become difficult to reprogram back to pluripotency, suggesting these regions highlight an epigenetic barrier to reprogramming. In addition, the major histone cluster Hist1 consistently becomes later replicating in committed cell types, and several histone H1 genes in this cluster are downregulated during differentiation, suggesting a possible instrument for the chromatin compaction observed during differentiation. Finally, we demonstrate that unknown samples can be classified independently using site-specific PCR against fingerprint regions. In sum, replication fingerprints provide a comprehensive means for cell characterization and are a promising tool for identifying regions with cell type-specific organization

Девочки чаще учатся на спортивных сборах по сравнению с мальчиками: роль тренера в гендерном разделении двух карьерных путей спортсменов

Рукопись поступила в редакцию: 21.01.2022.Received: 21.01.2022.В статье даются результаты исследования о роли тренера в мотивации спортсменов на построение двух карьер, а также их взглядов на двойную карьеру девушек и юношей. Результаты показали, что учащиеся-спортсмены в старших классах спортивных школ часто воспринимали созданный тренером мотивационный климат как нацеленный на достижение спортивного результата. Опрошенные спортсмены объяснили, что такой подход не мотивировал их на учебный процесс, а скорее обесценивал их образовательные цели. Выявлено, что тренеры, хотя и подчеркивали важность получения спортсменами среднего образования, не могли обосновать, как данные идеи включены в тренерскую практику. Тренеры согласились с тем, что те спортсмены, которые переходят в элитный спорт, должны сосредоточиться на развитии своей спортивной карьеры, при этом требования элитного спорта и высшего образования часто считались как несовместимые. Результаты показали, что стили коучинга играют важную роль в поддержке мотивации спортсменов к достижению целей двух карьер.The article presents the results of a study on the role of a coach in motivating athletes to build two careers, as well as their coaches’ views on the dual careers of girls and boys. The results have showed that student-athletes in high school of sports schools often perceived the motivational climate created by the coach as a process aimed at achieving sports results. The interviewed athletes explained that this approach did not motivate them to the learning process, and moreover, devalued their educational goals. It was revealed that although the coaches emphasized the importance of receiving secondary education for athletes, they could not justify how these ideas were included in coaching practice. The coaches have agreed that those athletes who switch to elite sports should focus on developing their sports career, while the requirements of elite sports and higher education were often considered incompatible. The results have showed that coaching styles play an important role in supporting the motivation of athletes to achieve the goals of two careers

Подростки-спортсмены строят двойную карьеру и благополучие в условиях двойного карьерного роста: роль факторов окружающей среды

Рукопись поступила в редакцию: 20.12.2021.Received: 20.12.2021.Цель исследования заключалась в изучении карьерного роста и благополучия спортсменов-подростков в условиях двойного карьерного роста. В исследовании выявлены особенности адаптивности к карьере в старших классах спортивной школы. В статье представлены данные относительно того, в какой степени самооценка и пол связаны с адаптивностью к двойной карьере, определены профили адаптации к карьере спортсменов-подростков, выявлены как ожидания студентов-спортсменов в зависимости от их успехов в спорте и учебе и соответствующие ожидания их родителей связаны с их профилями адаптации к карьере. Получены новые данные относительно того, как организационная культура спортивной школы влияет на построение карьеры спортсменов-подростков.The purpose of the scientific research was to study the career growth and well-being of adolescent athletes in conditions of dual career growth. The study revealed the features of adaptability to a career in high school of sports school. The article presents data on the extent to which self-esteem and gender are associated with adaptability to a dual career, the profiles of adaptation to the career of adolescent athletes have been defined, it is also revealed how the expectations of student-athletes depending on their success in sports and studies and the corresponding expectations of their parents are associated with their profiles of adaptation to a career. The new data on how the organizational culture of a sports school affects the career development of teenage athletes have been obtained

Состояния настроения студентов-спортсменов: профили развития, предпосылки и последствия

Рукопись поступила в редакцию: 14.01.2022.Received: 14.01.2022.Цель исследования заключается в получении информации о психическом здоровье молодых финских спортсменов старшего школьного возраста с точки зрения профилей состояний настроения. Было описано шесть разных профилей. Общий показатель настроения был выше у женщин, чем у мужчин. Энергетический индекс был самым высоким у мужчин в индивидуальных видах спорта и самым низким у мужчин в командных видах спорта. У женщин в индивидуальных видах спорта он был ниже, чем у мужчин в индивидуальных видах спорта, и выше в командных видах спорта, чем у мужчин. Он был выше у женщин в индивидуальных видах спорта, чем у женщин в командных видах спорта.The aim of the study is to obtain information about the mental health of young Finnish athletes of high school age in terms of mood state profiles. Six different profiles were described. The overall mood score of women was higher than of men. The energy index was the highest for the men in individual sports and the lowest one was for the men in team sports. For the women in individual sports, it was lower than for men in individual sports. For the women in team sports it was higher than for men in team sports. The energy index was higher for women in individual sports than for women in team sports