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PubMed1996

Effect of rotational atherectomy in noncalcified atherosclerotic plaque: a volumetric intravascular ultrasound study.

OBJECTIVES: This study used pre-rotational and post-rotational atherectomy volumetric intravascular ultrasound analysis to determine whether rotational atherectomy causes ablation of non-calcified atherosclerotic plaque. BACKGROUND: Rotational atherectomy is currently the preferred treatment for heavily calcified coronary lesions. However, the mechanism of lumen enlargement in noncalcified lesions has not been studied in detail. Intravascular ultrasound allows detailed, cross-sectional imaging of the coronary arteries in vivo. The normal coronary artery wall, the major components of the atherosclerotic plaque and the quantitative changes in vessel, lumen and plaque cross-sectional areas and volumes that occur as a result of the atherosclerotic disease process and during transcatheter therapy can be studied in a manner otherwise not possible. METHODS: Eighteen noncalcified native vessel lesions in 18 patients were imaged before and after rotational atherectomy using intravascular ultrasound systems incorporating motorized transducer pullback through a stationary imaging sheath. External elastic membrane, lumen and plaque plus media cross-sectional areas were measured every 1 mm of lesion length (for a total of 10 image slices), and external elastic membrane, lumen and plaque plus media volumes were calculated using Simpson's rule. RESULTS: After rotational atherectomy, the minimal lumen cross-sectional area increased from 1.37 +/- 0.50 to 2.99 +/- 0.60 mm2 (mean value +/- 1 SD, p < 0.0001). Lumen volume increased from 23.2 +/- 9.0 to 38.0 +/- 8.0 mm3 (p < 0.0001) as a result of a decrease in plaque plus media volume (from 102.2 +/- 50.9 to 85.8 +/- 47.7 mm3, p < 0.0001), with no change in total vessel (external elastic membrane) volume (125.3 +/- 54.2 to 123.8 +/- 52.9 mm3, p = 0.119). CONCLUSIONS: Rotational atherectomy effectively ablates noncalcified plaque in non-calcium-containing lesions.

Atherectomy, Coronary↗
PubMed2001

Shoulder MRI refinements: differentiation of rotator cuff tear from artifacts and tendonosis, and reassessment of normal findings.

One of the difficulties with rotator cuff imaging lies in the normal variability of the tendon's signal. There may be intermediate signal present within the tendon because of magic-angle phenomenon, muscle and tendon fiber interdigitation, or tendinopathy related to degenerative changes or overuse injury. Partial and complete rotator cuff tears should be distinguishable from these causes of intermediate signal if water signal is reliably identified. This article reviews the important issue of distinguishing between rotator cuff tear and other causes of high signal in the rotator cuff, including artifacts and tendonosis. We include a review of the literature and a brief report of a study we conducted on 20 shoulders of 14 asymptomatic, young volunteers. In this study, the rotator cuff tendons were evaluated for abnormal signal at different TE values to determine at what TE the interpreters were able to confidently distinguish the high-signal intensity of a tear (water) from the intermediate signal intensity associated with artifact and tendinopathy. Readers were able to distinguish water and tendon signal in 70% to 100% of fast-spin echo (FSE) fat-saturated images with TE of 66, but there was interobserver variability at this TE, suggesting that it is less reliable than 88 ms in the identification of rotator cuff tears. By using FSE fat-saturated sequences with TE of 88 and fast spin echo inversion recovery (FSEIR) sequences, readers at all levels of experience were able to differentiate water signal intensity from tendon signal intensity in 100% of cases. Therefore, we suggest that either FSEIR images or FSE fat-saturated images with TE greater than 66 be used to facilitate the differentiation of fluid signal from intermediate increased signal intensity in rotator cuff imaging. Additionally, this article reviews the normal findings of shoulder magnetic resonance imaging (MRI) as revealed by the asymptomatic subjects included in our study, and assesses these findings in respect to previous publications. The normal features reviewed include the subacromion-subdeltoid (SA/SD) bursa, the biceps tendon sheath, the acromioclavicular (AC) joint, and the greater tuberosity of the humerus. A small amount of fluid was commonly seen in the SA/SD bursa, as well as the biceps tendon sheath. Subjective down-sloping of the acromion in the coronal plane, mild degenerative change of the AC joint, and undersurface spurring of the AC joint were uncommon in our normal subjects. Cystic change limited to the posterior aspect of the greater tuberosity was identified in 15% to 45% of shoulders.

Artifacts↗
PubMed2004

Physician attitudes, opinions, and referral patterns: comparisons of those who have and have not taken an allergy/immunology rotation.

BACKGROUND: Interest in the field of allergy/immunology (A/I) is increasing, yet resident training programs are under pressure to shorten elective rotations such as A/I. It is unclear if there are differences between those who have and have not taken an A/I rotation. OBJECTIVE: To evaluate differences in the attitudes, opinions, and referral patterns between physicians who have and have not taken an A/I rotation. METHODS: An anonymous questionnaire was sent to 375 primary care physicians at one academic medical center. Subjects were separated into 5 cohorts based on specialty and level of training (internal medicine faculty, internal medicine resident, pediatric faculty, pediatric resident, and internal medicine-pediatric resident). RESULTS: Of the participants, 227 (61.0%) completed the survey. Compared with those who had not taken an A/I rotation, those who had taken an A/I rotation were more likely to feel they knew the types of cases seen by an allergist (75.9% vs 33.3%), to feel they knew an adequate amount about A/I (59.3% vs 19.5%), to feel they were exposed to an adequate amount of A/I during residency (64.8% vs 9.8%), to view immunotherapy as effective (70.0% vs 52.3%), and to have referred a patient to an allergist (77.8% vs 46.0%). CONCLUSIONS: There are significant differences in the attitudes, opinions, and referral patterns between physicians who have and have not taken an A/I rotation. Allergic diseases are increasing, yet residency training programs are under pressure to shorten rotations such as A/I to accommodate federally mandated work hour restrictions. The potential for inadequate care of allergic diseases may be an important issue if these trends continue.

Adult↗
PubMed2002

Rotational temperature of nitrogen glow discharge obtained by optical emission spectroscopy.

Measurements of rotational temperature as low as several hundred Kelvin have been measured using optical emission spectroscopy (OES) in nitrogen direct current (DC) glow discharge. The strongest band of the first negative system of nitrogen was chosen to deduce the rotational temperature at four different positions in nitrogen DC glow discharge, the back of cathode; cathode sheath; positive column; and anode glow. In positive column the rotational temperature increased apparently with the increasing discharge voltage from 500 to 1000 V when the pressure was 10 Pa. But with pressure of 20 Pa the rotational temperature in positive column increased slightly with the increase of discharge voltage. On the contrary, the rotational temperature in cathode sheath took reverse tendencies when the discharge voltage varies from 500 to 1000 V. As regard the anode glow, the rotational temperature at 10 Pa decreased with the increase of discharge voltage, but that at pressure of 20 Pa increased. We attribute the different tendencies of the rotational temperature to the different discharge statues at different pressures. When the discharge voltage varies from 500 to 1100 V, the discharge with pressure of 10 Pa is normal glow and that with 20 Pa is abnormal glow.

Nitrogen↗
PubMed1983

Rotational diffusion of Escherichia coli RNA polymerase free and bound to deoxyribonucleic acid in nonspecific complexes.

We have studied the rotational diffusion of Escherichia coli RNA polymerase free in solution and bound nonspecifically to DNA fragments. The rotational motion was measured by the decay in anisotropy of the triplet-triplet absorption by using as probes either the liganded enzyme inhibitor Rose Bengal or eosin 5'-isothiocyanate conjugated to the protein. The time resolution extended from 10 ns to 1 ms. Free RNA polymerase (holoenzyme) at high salt concentration (1 M NaCl) is monomeric and diffuses at 5 degrees C with a rotational correlation time of 0.66 microseconds, corresponding to an equivalent hydrodynamic sphere with a radius of 7.4 nm. These values and the known molecular weight are most compatible with a nonspherical shape, e.g., an oblate ellipsoid with an axial ratio of about 3. In 0.1 M NaCl, the holoenzyme is dimeric and has a rotational correlation time of 2 microseconds. The decay of anisotropy is at least biexponential upon binding RNA polymerase to calf thymus DNA or to poly[d(A-T)]. The fast component with half of the amplitude has decay kinetics comparable to those seen with the free monomeric enzyme. The slow component has a rotational correlation time of about 14 microseconds and is independent of DNA chain length in the range greater than 180 base pairs. Both rotational correlation times decrease with temperature, and the relative amplitudes change such that the faster component dominates at higher temperature. The rotational relaxation of the enzyme-DNA complexes is discussed in terms of alternative models involving rigid rod-sphere diffusion, conformational changes in the enzyme and/or DNA, sliding motions of the protein along the DNA, and torsional-bending motions of DNA envisioned as a deformable rod.

Circular Dichroism↗
PubMed1989

Rotational diffusion of mitochondrial ADP/ATP carrier studied by saturation-transfer electron spin resonance.

The rotational mobility of the mitochondrial ADP/ATP carrier has been studied solubilized in Triton micelles, reincorporated in phospholipid liposomes, and in mitochondria. Spin-labeled analogues of the noncovalent inhibitors carboxyatractyloside and atractyloside were found to be strongly immobilized when bound to the carrier [Munding, A., Beyer, K., & Klingenberg, M. (1983) Biochemistry 22, 1941-1947], such that saturation-transfer electron spin resonance spectroscopy could be used to study the rotational motion of the protein. Spin-labeled maleimide covalently bound to the carrier was found to have independent segmental motion and hence to be unsuitable for studies of protein rotation. The ESR spectra of the carboxyatractyloside and atractyloside spin labels were found to contain a second component from label in the lipid or detergent, necessitating the use of the saturation-transfer ESR integral method [Horváth, L. I., & Marsh, D. (1983) J. Magn. Reson. 54, 363-373] to analyze the rotational motion of the label component bound to the protein. Effective rotational correlation times obtained from integration of the high-field region of the spectrum were lower than those obtained from the total spectral integral, indicating strongly anisotropic rotational diffusion of the carrier in the vesicular and membrane systems, with the spin-label z axis oriented preferentially perpendicular to the rotation axis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

Heme distortions in sperm-whale carbonmonoxy myoglobin: correlations between rotational strengths and heme distortions in MD-generated structures.

We have investigated the effects of heme rotational isomerism in sperm-whale carbonmonoxymyoglobin using computational techniques. Several molecular dynamics simulations have been performed for the two rotational isomers A and B, which are related by a 180 degrees rotation around the alpha-gamma axis of the heme, of sperm-whale carbonmonoxy myoglobin in water. Both neutron diffraction and NMR structures were used as starting structures. In the absence of an experimental structure, the structure of isomer B was generated by rotating the heme in the structure of isomer A. Distortions of the heme from planarity were characterized by normal coordinate structural decomposition and by the angle of twist of the pyrrole rings from the heme plane. The heme distortions of the neutron diffraction structure were conserved in the MD trajectories, but in the NMR-based trajectories, where the heme distortions are less well defined, they differ from the original heme deformations. The protein matrix induced similar distortions on the hemes in orientations A and B. Our results suggest that the binding site prefers a particular macrocycle conformation, and a 180 degrees rotation of the heme does not significantly alter the protein's preference for this conformation. The intrinsic rotational strengths of the two Soret transitions, separated according to their polarization in the heme plane, show strong correlations with the ruffling deformation and the average twist angle of the pyrrole rings. The total rotational strength, which includes contributions from the chromophores in the protein, shows a weaker correlation with heme distortions.

Animals↗
PubMed2006

Microenvironment control of methyl rotation induced by proton transfer.

Methyl rotation induced by proton transfer was found for cis-N-methylacetamide (NMA). More interestingly, it was found that the microenvironment could control the methyl rotation. The atom-centered density matrix propagation (ADMP) method, a recently developed ab initio molecular dynamics, was further carried out to depict the trajectories for methyl rotation of NMA. Moreover, trajectories for methyl rotation of NMA complexed with water molecules were also calculated, and water molecules at the two different sites of NMA were found to reverse or cease the rotational direction of the methyl groups of NMA. This finding that microenvironment can not only control rotational direction of methyl groups but can also cease the rotation may be of significant importance for the control of molecular machines.

Journal Article↗
PubMed2004

Correlation times and adiabatic barriers for methyl rotation in SNase.

The relation of rotational correlation times to adiabatic rotational barriers for alanine methyl groups in staphylococcal nuclease (SNase) is investigated. The hypothesis that methyl rotational barriers may be useful probes of local packing in proteins is supported by an analysis of ten X-ray crystal structures of SNase mutants. The barrier heights are consistent across a set of ten structures of a native SNase and mutants containing single-point mutations or single or double insertions, most in a ternary SNase complex. The barriers for different methyls have a range of 7.5 kcal/mol, which at 300 K would correspond to a five-order-of-magnitude range in correlation time. It is demonstrated that adiabatic rotational barriers can fluctuate significantly during an MD simulation of hydrated SNase, but that a Boltzmann weighted average is predictive of rotational correlation times determined from correlation functions. Even if a given methyl is on average quite sterically hindered, infrequently sampled low-barrier conformations may dominate the Boltzmann distribution. This result is consistent with the observed uniformity of NMR correlation times for (13)C-labeled methyls. The methyl barriers in simulation fluctuate on multiple time scales, which can make the precise relationship between methyl rotational correlation time and methyl rotation barriers complicated. The implications of these issues for the interpretation of correlation times determined from NMR and simulation are discussed.

Alanine↗
PubMed1997

A large sex difference on a two-dimensional mental rotation task.

Mental rotation tests require participants to identify rotated versions of a target stimulus. The Vandenberg Mental Rotations Test depicts rotations in 3-D space and typically yields one of the largest established cognitive sex differences favoring males. It is presently unclear whether this male advantage is related to the nature of rotations depicted in 3-D space or to the high level of difficulty of this task. The present study developed a new test depicting picture plane, or 2-D, rotations. When task difficulty within this 2-D test was varied, a male advantage as large as that seen on the Vandenberg test was found for the difficult component. These findings suggest that processing in 3 dimensions is not a necessary condition for a large sex difference on tests of mental rotation.

Adult↗
PubMed2001

The four final rotation states of Venus.

Venus rotates very slowly on its axis in a retrograde direction, opposite to that of most other bodies in the Solar System. To explain this peculiar observation, it has been generally believed that in the past its rotational axis was itself rotated to 180 degrees as a result of core-mantle friction inside the planet, together with atmospheric tides. But such a change has to assume a high initial obliquity (the angle between the planet's equator and the plane of the orbital motion). Chaotic evolution, however, allows the spin axis to flip for a large set of initial conditions. Here we show that independent of uncertainties in the models, terrestrial planets with dense atmosphere like Venus can evolve into one of only four possible rotation states. Moreover, we find that most initial conditions will drive the planet towards the configuration at present seen at Venus, albeit through two very different evolutionary paths. The first is the generally accepted view whereby the spin axis flips direction. But we have also found that it is possible for Venus to begin with prograde rotation (the same direction as the other planets) yet then develop retrograde rotation while the obliquity goes towards zero: a rotation of the spin axis is not necessary in this case.

Journal Article↗
PubMed2006

A regular period for Saturn's magnetic field that may track its internal rotation.

The rotation rate of a planet is one of its fundamental properties. Saturn's rotation, however, is difficult to determine because there is no solid surface from which to time it, and the alternative 'clock'--the magnetic field--is nearly symmetrically aligned with the rotation axis. Radio emissions, thought to provide a proxy measure of the rotation of the magnetic field, have yielded estimates of the rotation period between 10 h 39 min 22 s and 10 h 45 min 45 s (refs 8-10). Because the period determined from radio measurements exhibits large time variations, even on timescales of months, it has been uncertain whether the radio-emission periodicity coincides with the inner rotation rate of the planet. Here we report magnetic field measurements that revealed a time-stationary magnetic signal with a period of 10 h 47 min 6 s +/- 40 s. The signal appears to be stable in period, amplitude and phase over 14 months of observations, pointing to a close connection with the conductive region inside the planet, although its interpretation as the 'true' inner rotation period is still uncertain.

Journal Article↗
PubMed2005

Rotational spectra and structure of the Ar2-H2S complex: pulsed nozzle Fourier transform microwave spectroscopic and ab initio studies.

This paper reports the rotational spectrum and structure of the Ar2-H2S complex and its HDS and D2S isotopomers. The ground state structure has heavy-atom C2v symmetry with the two Ar atoms indistinguishable and H2S freely rotating as evinced by the fact that asymmetric top energy levels with Kp=odd levels are missing. The rotational constants for the parent isotopomer are: A=1733.115(1) MHz, B=1617.6160(5) MHz and C=830.2951(2) MHz. Unlike the Ar-H2S complex, the Ar2-H2S does not show an anomalous isotopic shift in rotational constants on deuterium substitution. However, the intermolecular potential is still quite floppy, leading to very different centrifugal distortion constants for the three isotopomers. The Ar-Ar and Ar-c.m.(H2S) distances are determined to be 3.820 A and 4.105 A, respectively. The A rotational constants for Ar2-H2S/HDS/D2S isotopomers are very close to each other and to the B constant of free Ar2, indicating that H2S does not contribute to the moment of inertia about the a-axis. Ab initio calculations at MP2 level with aug-cc-pVQZ basis set lead to an equilibrium C2v minimum structure with the Ar-Ar line perpendicular to the H-H line and the S away from Ar2. The centrifugal distortion constants, calculated using the ab initio force field, are in reasonable agreement with the experimental values. However, they do not show the variation observed for different isotopmers. The binding energy of Ar2-H2S has been determined to be 507 cm-1(6.0 kJ mol-1) by CBS extrapolation after correcting for basis set superposition error. Potential energy scans point out that the barrier for internal rotation of H2S about its b axis is only 10 cm-1 and it is below the zero point energy (13.5 cm-1) in this torsional degree of freedom. Internal rotation of H2S about its a- and c-axes also have small barriers of about 50 cm-1 only, suggesting that H2S is extremely floppy within the complex.

Argon↗
PubMed2002

A longitudinal study of condylar growth and mandibular rotation in untreated subjects with class II malocclusion.

Condylar growth intensity, mandibular growth rotation, and the association between growth intensity and rotation were evaluated in 32 untreated subjects with Class II malocclusions. Condylar growth was measured on serial lateral head films annually from ages 8 to 13. The analysis showed that the growth intensity of the condyles varied only slightly between girls and boys, with boys growing more. Fluctuations in growth intensity were observed in all subjects from year to year. None of the individuals maintained a consistent growth velocity over two or more consecutive years. The average condylar growth intensity was two to three mm per year throughout the period from age 8 1/2 to 12 1/2 for both sexes, with boys growing slightly faster than girls at some ages. The greatest growth velocity observed was eight mm in one year, which was seen in one boy. Three girls had as much as six mm of condylar growth in one year. Average mandibular rotation was -0.8 (+/- 0.5 SD) per year in boys and -0.6 degrees (+/- 0.6 SD) in girls, with great individual variation for both sexes. Ninety percent of the subjects showed some degree of anterior or forward rotation; only one subject demonstrated posterior rotation and three demonstrated almost no rotation. No clear relationship was found between amount of condylar growth and mandibular rotation. This study shows that condylar growth intensity varies considerably between subjects and from year to year in each subject, and suggests that clinicians need to be conservative when estimating treatment length for a patient with a Class II malocclusion.

Adolescent↗
PubMed2000

Cardiac rotation and relaxation in patients with aortic valve stenosis.

BACKGROUND: Diastolic dysfunction with delayed relaxation and abnormal passive elastic properties has been described in patients with severe pressure overload hypertrophy. The purpose of this study was to evaluate the time course of rotational motion of the left ventricle in patients with aortic valve stenosis using myocardial tagging. METHODS: Myocardial tagging is a non-invasive method based on magnetic resonance which makes it possible to label ('tag') specific myocardial regions. From the motion of the tag's cardiac rotation, radial displacement and translational motion can be determined. In 12 controls and 13 patients with severe aortic valve stenosis systolic and diastolic wall motion was assessed in an apical and basal short axis plane. RESULTS: The normal left ventricle performs a systolic wringing motion around the ventricular long axis with clockwise rotation at the base (-4.4+/-1.6 degrees) and counter-clockwise rotation at the apex (+6.8+/-2.5 degrees) when viewed from the apex. During early diastole an untwisting motion can be observed which precedes diastolic filling. In patients with aortic valve stenosis systolic rotation is reduced at the base (-2.4+/-2.0 degrees; P<0.01) but increased at the apex (+12.0+/-6.0 degrees; P<0.05). Diastolic untwisting is delayed and prolonged with a decrease in normalized rotation velocity (-6.9+/-1.1 s(-1)) when compared to controls (-10.7+/-2.2 s(-1); P<0.001). Maximal systolic torsion is 8.0+/-2.1 degrees in controls and 14.1+/-6.4 degrees (P<0.01) in patients with aortic valve stenosis. CONCLUSIONS: Left ventricular pressure overload hypertrophy is associated with a reduction in basal and an increase in apical rotation resulting in increased torsion of the ventricle. Diastolic untwisting is delayed and prolonged. This may explain the occurrence of diastolic dysfunction in patients with severe pressure overload hypertrophy.

Adult↗
PubMed2006

Concentric and eccentric muscle fatigue of the shoulder rotators.

Previous research has demonstrated fatigue resistance for eccentric compared with concentric muscle contractions in the lower extremity. The purpose of this study was to determine if eccentric fatigue resistance was also evident in the internal and external rotators of the shoulder. Ten subjects performed three sets of 32 maximum isokinetic contractions in shoulder internal and external rotation at 120 degrees /s. One arm performed eccentric contractions and the contralateral arm performed concentric contractions. Subjects were also tested for isometric strength prior to and immediately following the isokinetic contractions. Percent change in isokinetic torque (first five repetitions versus last five for each set) and isometric torque was compared between the arms performing eccentric and concentric contractions. Fatigue with isokinetic contractions was not different between eccentric and concentric internal rotation (25 % vs. 26 %, p = 0.76) and external rotation (24 % vs. 32 %, p = 0.11). Similarly, fatigue with isometric contractions was not different between eccentric and concentric internal rotation (11 % vs. 5 %. p = 0.33) and external rotation (15 % vs. 7 %, p = 0.07). These results indicate that unlike previously described fatigue resistance for eccentric muscle contractions in the quadriceps, dorsiflexors and plantarflexors, fatigue was not different between eccentric and concentric muscle contractions of the internal and external rotators of the shoulder.

Adult↗
PubMed1993

[Laser versus rotation angioplasty in the recanalization of chronic femoropopliteal arterial occlusions].

Between June 1987 and July 1989 laser angioplasty, and between July 1989 and December 1991 rotation angioplasty was used as the method of choice for the recanalisation of chronic (minimal duration 3 months) arterial occlusions in the femoro-popliteal region. The technical success rate and final results following supplementary balloon dilatation were identical and there was no significant difference between the two groups (laser 87%, rotation 87.7%). For long occlusions (more than 150 mm), the success rate for rotation angioplasty was 60% and significantly higher than for laser angioplasty at 40%. Complication rates for rotation angioplasty were 24.3%, higher than laser angioplasty with 20.3%. This was due to the higher incidence of emboli of 12.1% compared with the laser technique of 7.3%. Cumulative patency rates after two years showed no significant difference (uncorrelated/correlated: laser 53.4%/67.8%; rotation 56.6%/67.5%). Using lytic and aspiration techniques, the higher incidence of embolisation during rotation angioplasty had no adverse effect on final outcome. If both methods are available, it is advisable to treat long occlusions by rotation angioplasty because of the high immediate success rate, whereas short occlusions are best dealt by laser angioplasty because of the lower incidence of embolisation.

Aged↗
PubMed2004

Discrete and heterogeneous rotational dynamics of single membrane probe dyes in gel phase supported lipid bilayer.

In order to probe the local dynamics of lipid bilayers in the gel phase, we measured the rotational time trajectories of a membrane probe, diI(3), in supported bilayers of DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) using single molecule fluorescence polarization imaging. diI(3) has two hydrocarbon tails that mimic phospholipid tails and has its transition dipole moment lying mostly on the plane of the membrane; hence it is an excellent probe for rotational dynamics in membranes. Above the transition temperature, the probes are laterally mobile and do not display polarized emission. In the gel phase below the transition temperature, lateral mobility is severely reduced and the emission becomes polarized with its polarization direction changing in the milliseconds time scale. Molecule by molecule analysis of the rotational time scales revealed significant heterogeneities among molecules, much larger than would be due to statistical noise. Control experiments using small unilamellar vesicles suggest that the heterogeneities are not caused by surface interactions and are intrinsic to the gel phase membrane. The rotational dynamics is strongly temperature dependent and the thermally activated state for the rotational motion has a large entropic barrier (> 30kB), indicating that relatively large local disorder is required for the rotational motion to occur. Rotational hopping between discrete angles has been observed at the lowest temperatures (approximately 10 degrees C). Our results suggest that the gel phase membrane is not uniform at the microscopic level but is highly dynamic with the rigidity of local environments constantly changing.

Carbocyanines↗