scholarly journals Generating and sustaining long-lived spin states in 15N,15N′-azobenzene

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kirill F. Sheberstov ◽  
Hans-Martin Vieth ◽  
Herbert Zimmermann ◽  
Bogdan A. Rodin ◽  
Konstantin L. Ivanov ◽  
...  
Keyword(s):  
Singlet State ◽  
Relaxation Times ◽  
Great Promise ◽  
Spin States ◽  
Longitudinal Relaxation Time ◽  
Challenging Problem ◽  
Photochromic Properties ◽  
Spin Pair ◽  
Spin Order ◽  
A Value

AbstractLong-Lived spin States (LLSs) hold a great promise for sustaining non-thermal spin order and investigating various slow processes by Nuclear Magnetic Resonance (NMR) spectroscopy. Of special interest for such application are molecules containing nearly equivalent magnetic nuclei, which possess LLSs even at high magnetic fields. In this work, we report an LLS in trans-15N,15N′-azobenzene. The singlet state of the 15N spin pair exhibits a long-lived character. We solve the challenging problem of generating and detecting this LLS and further increase the LLS population by converting the much higher magnetization of protons into the 15N singlet spin order. As far as the longevity of this spin order is concerned, various schemes have been tested for sustaining the LLS. Lifetimes of 17 minutes have been achieved at 16.4 T, a value about 250 times longer than the longitudinal relaxation time of 15N in this magnetic field. We believe that such extended relaxation times, along with the photochromic properties of azobenzene, which changes conformation upon light irradiation and can be hyperpolarized by using parahydrogen, are promising for designing new experiments with photo-switchable long-lived hyperpolarization.

scholarly journals Coherent evolution of singlet spin states in PHOTO-PHIP and M2S experiments

2017 ◽  
Vol 19 (38) ◽  
pp. 25961-25969 ◽  
Author(s):  
A. N. Pravdivtsev ◽  
A. V. Yurkovskaya ◽  
P. A. Petrov ◽  
H.-M. Vieth
Keyword(s):  
Singlet State ◽  
Spin States ◽  
Free Evolution

Observing the free evolution of a pure singlet state allows one to obtain a 2D ZQ spectrum (ΔJ spectrum).

scholarly journals THE EFFECT OF POLYANILINE CONTENT DEPOSITED ON SILICA GEL PARTICLES ON THE ELECTRORHEOLOGY OF SILICONE-OIL SUSPENSIONS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1097-1103 ◽  
Author(s):  
V. PAVLÍNEK ◽  
P. SÁHA ◽  
T. KITANO ◽  
J. HROMÁDKOVÁ ◽  
J. STEJSKAL ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Silicone Oil ◽  
Relaxation Times ◽  
Content Volume ◽  
Interfacial Polarization ◽  
Secondary Importance ◽  
Frequency Spectra ◽  
Pure Silica ◽  
A Value ◽  
Dc Electric Field

Investigation of the electrorheological effect of silicone-oil suspensions of silica particles coated with polyaniline base in a DC electric field revealed that breaking stress, as a criterion the intensity of the electrorheological phenomenon, steeply increased at first with coating thickness. At relatively low polyaniline content (volume fraction ≈ 0.05), it has reached a value several times higher than that with suspension of pure silica. Then they became virtually constant or slightly increased. The frequency spectra of dielectric characteristics of these systems reflect high relaxation times. The results suggest that the interfacial polarization of particles is predominantly controlled by polarizability of their surface layer, and the influence of the thickness is of secondary importance.

On the relationship between Phanerozoic diversity and changes in habitable area

Paleobiology ◽  
1978 ◽  
Vol 4 (3) ◽  
pp. 359-366 ◽  
Author(s):  
Karl W. Flessa ◽  
J. John Sepkoski
Keyword(s):  
Aquatic Organisms ◽  
Great Promise ◽  
Sampling Efficiency ◽  
A Value ◽  
Residual Variation ◽  
Mixed Support ◽  
Marine Diversity ◽  
Species Area ◽  
Taxonomic Range ◽  
The Relationship

Applications of the species-area equation to studies of fluctuations in Phanerozoic diversity have great promise but can involve questionable assumptions. Sepkoski's (1976) analysis of marine diversity throughout the Phanerozoic record assumes that total rock volume is a sufficient measure of sampling efficiency and that an isomorphous equation is appropriate for all of Phanerozoic time. The area of marine sedimentary rock and the area of continental seas are not independent variables. Residual variation in diversity (that which remains after subtracting the effects of rock volume) might be explained by either the species-area relationship or by another component of sampling efficiency. A species-area equation in which the slope (z) and intercept (k) are assumed constant receives mixed support from arguments based on Recent terrestrial and aquatic organisms. Observed z-values cluster near a value of 0.30 despite a wide taxonomic range, but are generally below those found for the Phanerozoic record. Temporal fluctuations in k values, in response to changes in the area of continental seas, may produce elevated estimates of z.

scholarly journals Determination of the Empirical Electrokinetic Equilibrium Condition of Microorganisms in Microfluidic Devices

Biosensors ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 148
Author(s):  
Adriana Coll De Peña ◽  
Nicole Hill ◽  
Blanca H. Lapizco-Encinas
Keyword(s):  
Equilibrium Condition ◽  
Microfluidic Devices ◽  
Great Promise ◽  
The Novel ◽  
Emerging Pathogens ◽  
Present Contribution ◽  
A Value ◽  
Current Estimation ◽  
Experimental Values

The increased concern regarding emerging pathogens and antibiotic resistance has drawn interest in the development of rapid and robust microfluidic techniques to analyze microorganisms. The novel parameter known as the electrokinetic equilibrium condition (EEEC) was presented in recent studies, providing an approach to analyze microparticles in microchannels employing unique electrokinetic (EK) signatures. While the EEEC shows great promise, current estimation approaches can be time-consuming or heavily user-dependent for accurate values. The present contribution aims to analyze existing approaches for estimating this parameter and modify the process into an accurate yet simple technique for estimating the EK behavior of microorganisms in insulator-based microfluidic devices. The technique presented here yields the parameter called the empirical electrokinetic equilibrium condition (eEEEC) which works well as a value for initial approximations of trapping conditions in insulator-based EK (iEK) microfluidic systems. A total of six types of microorganisms were analyzed in this study (three bacteria and three bacteriophages). The proposed approach estimated eEEEC values employing images of trapped microorganisms, yielding high reproducibility (SD 5.0–8.8%). Furthermore, stable trapping voltages (sTVs) were estimated from eEEEC values for distinct channel designs to test that this parameter is system-independent and good agreement was obtained when comparing estimated sTVs vs. experimental values (SD 0.3–19.6%). The encouraging results from this work were used to generate an EK library of data, available on our laboratory website. The data in this library can be used to design tailored iEK microfluidic devices for the analysis of microorganisms.

scholarly journals Conversions of Localized Excess Electrons and Spin States under External Electric Field: Inter-Cage Electron-transfer Isomer (C20F20)3&K2

2020 ◽  
Author(s):  
Jia-Min Tang ◽  
Yin-Feng Wang ◽  
Tian Qin ◽  
Xue-Xia Liu ◽  
Zhijun Wang ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electric Field ◽  
External Electric Field ◽  
Singlet State ◽  
Lone Pair ◽  
Open Shell ◽  
Spin States ◽  
New Members ◽  
Excess Electrons ◽  
State 1

By doping two potassium atoms among three CF cages, peanut-shaped single molecular solvated dielectron (CF)&K was theoretically presented. The triplet structures with two excess electrons individually inside left and middle cages (isomers I or II) are thermodynamically more stable than both open-shell (OS) and close-shell (CS) singlet ones with lone pair of excess electrons inside middle cage. Applying an oriented external electric field (OEEF) of -20 × 10 au (-0.1018 V/Å) or a larger one can result in both left-to-right transfers of the two excess electrons, and then releasing the OEEF can form new kind of inter-cage electron-transfer isomers (III or IV). Each triplet I ~ IV with three redox sits may be new members of mixed-valent compounds, namely, Robin-Day Class II. For electrified I of (CF)&K , the following spin states are ground state: 1) triplet state in field ranges of -120 × 10 < F < -30 × 10 au and 30 × 10 < F < 111 × 10 au; 2) CS singlet state in range of F ≥ 111 × 10 and ≤ -120 × 10 au; 3) OS singlet state in ranges of -30 × 10 ≤ F ≤ -5 × 10 au and 5 × 10 ≤ F ≤ 30 × 10 au.

Proton NMR-Relaxation Dispersion in Meconium Solutions and Healthy Amniotic Fluid: Possible Applications to Medical Diagnosis

1982 ◽  
Vol 37 (5-6) ◽  
pp. 394-398 ◽  
Author(s):  
Georges J. Béné ◽  
Bernard Borcard ◽  
Volker Graf ◽  
Emile Hiltbrand ◽  
Patric Magnin ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Amniotic Fluid ◽  
Medical Diagnosis ◽  
High Field ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Field Measurements ◽  
Relaxation Dispersion ◽  
Longitudinal Relaxation Time ◽  
Relaxation Experiments

Abstract In order to show that for a possible application in medical diagnosis NMR-relaxation experiments at low Larmor frequencies (v0 ≤ 20 kHz) are more sensitive than the up to now done high field measurements in the MHz-range, we present dispersion curves (v0 = 50 Hz to 50 MHz) of the proton longitudinal relaxation time T1 and values of the transversal relaxation time T2 for the example of amniotic fluids. Only for Larmor frequencies below ≃ 100 kHz the relaxation times for healthy amniotic fluid and pathological meconium solutions are significantly different, whereas at high Larmor frequencies, i. e. in the conventional MHz-range, the observed changes are rather small.

scholarly journals Reorientation of thiophene molecules in a benzene lattice

1978 ◽  
Vol 56 (5) ◽  
pp. 714-716 ◽  
Author(s):  
William E. Sanford ◽  
Robert K. Boyd ◽  
John A. Ripmeester
Keyword(s):  
Composition Range ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Intermolecular Forces ◽  
Spin Lattice Relaxation ◽  
Plane Rotation ◽  
Spin Lattice ◽  
A Value ◽  
Experimental Activation Energy ◽  
Thiophene Molecule

Benzene and thiophene are known to form solid solutions over the entire composition range; the present work demonstrates the orientational freedom of thiophene molecules in solid solution with excess perdeuterobenzene, through measurements of spin–lattice relaxation times. In addition, the atom–atom approximation to intermolecular forces yielded a potential energy profile for in-plane rotation of a thiophene molecule, embedded in a benzene lattice, which is consistent with the experimental activation energy for the relaxation. The second moment of the absorption signal for thiophene in perdeuterobenzene at 80 K was determined to be 0.66 G2, compared with a value of 0.42 G2 computed as the intramolecular contribution only for in-plane rotation

The primary process in the photolysis of hexafluoroacetone vapour III. The efficiency of intersystem crossing

1968 ◽  
Vol 306 (1487) ◽  
pp. 529-536 ◽  
Keyword(s):  
Quantum Yield ◽  
Lower Limit ◽  
Singlet State ◽  
Excited Singlet State ◽  
Intersystem Crossing ◽  
Primary Process ◽  
Excited Singlet ◽  
A Value ◽  
Low Concentrations

The value of k 6 /( k 4 + k 5 + k 6 ) (mechanism of part I) was determined by two techniques, namely the sensitization of the isomerization of cis - to trans -butene-2 and the sensitization of the phosphorescence of biacetyl. Both techniques yielded a value for the ratio of 0⋅9 ± 0⋅1. The value obtained by the isomerization technique is a lower limit because the quantum yield for the isomerization did not attain a value independent of [ cis -butene-2], but reached a maximum at low concentrations of olefine and then decreased. A similar scavenging of the excited singlet state of hexafluoroacetone was observed when biacetyl was present as an addend. However, in both cases the measurements were made with sufficiently low concentrations of addend that the singlet scavenging should have introduced less, than 10% error. It is concluded that reaction (5) of the mechanism cannot be an important mode of disappearance of excited ketone molecules.

A feasibility study of Dignity Psychotherapy delivered via telemedicine

2004 ◽  
Vol 2 (2) ◽  
pp. 149-155 ◽  
Author(s):  
STEVEN D. PASSIK ◽  
KENNETH L. KIRSH ◽  
SUZANNE LEIBEE ◽  
LISA S. KAPLAN ◽  
CELIA LOVE ◽  
...  
Keyword(s):  
Feasibility Study ◽  
Great Promise ◽  
A Value ◽  
Dignity Therapy ◽  
Level Of Satisfaction ◽  
Timely Fashion ◽  
Dying At Home ◽  
High Level ◽  
Therapy Sessions

Objective: Dignity Psychotherapy has shown great promise as a value-affirming intervention for patients with advanced disease. We delivered the Dignity Psychotherapy intervention in a feasibility study of a series of eight cancer patients via videophone technology to deliver the therapy into their homes.Methods: Once eligible patients were consented on this IRB-approved study, they completed baseline assessments and were scheduled to have the videophone placed in their homes. The Dignity Therapy sessions then encompassed a first session, which was transcribed and edited, followed by a second session to go over the edited transcript and allow the patient to make changes. Patients then filled out follow-up questionnaires and had the telemedicine equipment removed from their homes, and their legacy document delivered.Results: Participants had a mean age of 56.32 years (range = 41–66, SD = 7.65) and were diagnosed with lung (n = 5, 62.5%), breast (n = 2, 25%), or colon cancer (n = 1, 12.5%). They reported overall benefit from the intervention along with a high level of satisfaction. We were able to deliver the intervention in a timely fashion, with minimal length between sessions and transcript delivery and few technical difficulties.Significance of results: Telemedicine can greatly extend the benefits of Dignity Psychotherapy by bringing it to patients who are dying at home. Our very preliminary work suggests that delivering the intervention to patients who are too ill to leave their homes or who are in rural locations may be a feasible way to help them.

Fluorescence différée et émissions photostimulées du carbazole et de la diphénylamine dans une matrice rigide d'éther à 77 °K

1974 ◽  
Vol 52 (22) ◽  
pp. 3707-3715 ◽  
Author(s):  
D. Muller ◽  
M. Ewald ◽  
G. Durocher
Keyword(s):  
Singlet State ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Constant Ratio ◽  
Light Stimulation ◽  
Excited Singlet ◽  
A Value ◽  
Rate Constant Ratio ◽  
Experimental Values ◽  
Triplet Quantum Yields

The isothermal delayed fluorescence along with the visible (6000 Å) photostimulated fluorescence and phosphorescence emissions have been recorded and analyzed in the following systems: diphénylamine (DPA) – ether rigid glass and carbazole (C) – ether rigid glass at 77°K. The electron–cation recombination after visible light stimulation has been analyzed in terms of a kinetic model already described (10). The triplet quantum yields of the DPA and C molecules are calculated and compared to the existing experimental values. The rate constant ratio (β) of populating the first triplet (T1) relative to populating the first excited singlet (S1) after the recombination event has taken place, is equal to about 2 in both systems investigated here. A value of 4.4 was obtained for indole and tryptophan in the same matrix. This difference can only be explained in terms of various singlet state energies for these molecules and also in terms of the stimulating energies used in these experiments.

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