313 research outputs found
Erratum: “A 250 GHz ESR study of o-terphenyl: Dynamic cage effects above Tc” [J. Chem. Phys. 106, 9996 (1997)]
No full textResponse to “Comment on ‘A 250 GHz ESR study of o-terphenyl dynamic cage effects above T[sub C]’ ” [J. Chem. Phys. 109, 10523 (1998)]
No full textWe address the points raised by Giordano and Leporini (GL) and show that accounting properly for the nonexponential decay of the rotational correlation function leads to improved agreement with the Stokes–Einstein–Debye (SED) relation above the crossover temperature TC for those probes 3,3′-dimethyloxazolidinyl-N-oxy-2′,3-5α-cholestane (CSL), and perdeuterated 2,2′,6,6′-tetramethyl-4-methyl aminopiperidinyl-N-oxide) (MOTA) that are well-coupled to the viscous modes of o-terphenyl (OTP) when the average relaxation rate 1⁄6〈τ〉 is plotted versus 1/T. On the other hand, 2,2′,6,6′-tetramethyl-4-piperidine-N-oxide (PDT) shows simple Arrhenius behavior in this regime, because of weak coupling to the solvent cage, inconsistent with SED, which was clearly shown in our paper. We also suggest that the difference in chemical structure of the PDT probe, studied by us, compared to 2,2′,6,6′-tetramethylpiperidine-N-oxyl (TEMPO), studied by GL, accounts for the difference in the low-temperature relaxation behavior of the two probes
A 250 GHz ESR study of o-terphenyl: Dynamic cage effects above T-c
No full textThree nitroxide spin probes of different sizes and geometrical shape were used in a 250 GHz ESR study of the probe rotational dynamics in the fragile glass former ortho-terphenyl (OTP) over a wide temperature range from 380 to 180 K. Comparative studies at 9.5 GHz have also been performed. Perdeuterated 2,2′,6,6′-tetramethyl-4-methyl aminopiperidinyl-N-oxide (MOTA), and 3,3-dimethyloxazolidinyl-N-oxy-2′,3-5α-cholestane (CSL) are, respectively, comparable in size to and larger than the OTP host molecule, whereas Perdeuterated 2,2′,6,6′-tetramethyl-4-piperidine-N-oxide (PDT) is substantially smaller. The sensitivity of 250 GHz ESR to the details of the rotational tumbling for T≳Tc (where Tc is the crossover temperature) was exploited to show that the relaxation is fit by a model that is characteristic of a homogeneous liquid. A nonlinear least-squares analysis shows that below the melting point, Tm, CSL, and MOTA dynamics are well-described by a model of dynamic cage relaxation proposed by Polimeno and Freed wherein the probe relaxation is significantly influenced by a fluctuating potential well created by the neighboring OTP molecules. A model of simple Brownian reorientation does not fit the experimental spectra of CSL or MOTA as well as the dynamic cage model below Tm. Spectra of PDT do not show any significant non-Brownian dynamics for this probe. It was found that the characteristic rates of the cage model, viz., the reorientation of the probe and the cage relaxation, were describable by activated processes; however, the “average” rotational diffusion rates (defined in the usual manner as the time integral of the correlation function) derived from the dynamic cage parameters follow the Stokes–Einstein–Debye (SED) relation rather well, in agreement with previous studies by other physical techniques. It is then shown that the usual stretched exponential fit to the motional correlation function, interpreted in terms of an inhomogeneous distribution of simple reorientational rates, is clearly inconsistent with the observed ESR spectrum. The absence of a significant cage potential above Tm is discussed in terms of a model of frustration limited domain sizes proposed by Kivelson and co-workers. Evidence for the existence of substantial voids in OTP below Tm, especially from the spectra of the small PDT probe, is discussed in terms of the structure and packing of the OTP solvent
Influence of aligning materials on dielectric behaviour of surface stabilised FLC cells
No full textProceedings of SPI
Effects of Eccentric Training Intervention on Performance During the Sprint, Drag, Carry Event of the Army Combat Fitness Test
No full textThesis (MS) - Indiana University, Kinesiology Department/School of Public Health, 2023The purpose of this study was to determine the effect of introducing eccentrically focused movements into a normal Military training program on the Army Combat Fitness Test (ACFT). The fourth event of the test, the Sprint Drag Carry, was the focus of the research. Eccentric training has been shown to elicit a sprint performance benefit 10,13,19,27 as well as decrease injury prevalence 17,20,28,34,36, It was hypothesized that including eccentric movements would improve performance for this 250m shuttle sprint event. Twenty-two Cadets from the Indiana University ROTC program were recruited to participate in a 6-week training program. Participants were randomly assigned to one of two groups to conduct either 3 x 5 repetitions of a Nordic Complex (combination of Nordic hamstring curl and reverse Nordic hamstring curl) or 3 x 15 repetitions of a tempo-based body weight squat. Participants took a pre and post ACFT to measure the change in performance. Overall ACFT scores as well as three of the six events showed significant improvement; 3.1% (p<.001) improvement in overall score (out of 600), 6.7% (p=.001) improvement in Hex bar deadlift, 2.7% (p=.045) improvement to 2-mile run time, and 10.4 % (p<.001) improvement in Sprint Drag Carry performance from pre to post with no differences between groups. No injuries were reported during the training period. The results demonstrate there was an observed improvement from pre to post-test; however, it is more likely a result of a dedicated training program designed by the Army to improve ACFT performance than the addition of the movements
Job handling/Error recovery with the EGEE prototype & Proxy Service and Roaming Access
No full textCERN, GANGA workshop, April 200
DIANE - distributed analysis environment for Grid-enabled simulation and analysis of physics data
No full textDistributed analysis environment (DIANE) is the result of R&D in CERN IT Division focused on interfacing semi-interactive parallel applications with distributed Grid technology. DIANE provides a master-worker workflow management layer above low-level Grid services. DIANE is application and language-neutral. Component- container architecture and component adapters provide flexibility necessary to fulfill the diverse requirements of distributed applications. Physical transport layer assures interoperability with existing middleware frameworks based on Web services. Several distributed simulations based on Geant 4 were deployed and tested in real-life scenarios with DIANE. (9 refs)
Ignacy Mościcki (1867 - 1946) - chemist or electrician?
No full textThe paper presents the curriculum vitae of Ignacy Moscicki, starting with his education in high school in Plock and chemical studies at the Technical University in Riga. It briefly presents his revolutionary activities in the country and the necessity of his departure to London. His stay in Switzerland at the University of Freiburg is also described. There, in 1901, he began his research on the acquisition of nitrogen from the air. He discovered that the intensity of obtaining the product increases in the arc of high voltage and high frequency. These studies led to the necessity of building a high-voltage installations which had never been constructed before. In this area he also showed his inventiveness, as well as his skills as a constructor and technologist (Moscicki capacitors), he also proved to be a talented businessman. He would eventually become a wealthy man with great scientific authority. In 1912 he was invited to take the chair at the State Polytechnic University of Lvov. His reasons and motivation that led to leaving Switzerland and moving to Lvov are presented. The paper also describes his activities in the domestic industry, which began during the First World War, and which greatly expanded (Chorzow, Moscice etc.) after Poland regained independence. A list of his most important publications and patents is attached
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