Kinetics of near-infrared-to-visible upconversion in rubrene: An initial excitation of triplets

AbstractTime resolved surface second harmonic generation has been used to probe the photoreduction kinetics of malachite green adsorbed onto single crystal cadmium sulfide. A detailed analysis is presented of how the adsorbates and the noncentrosymmetric substrate contribute separately to the total second harmonic signal. Conditions under which the adsorbates can be cleanly detected are described. To complement kinetic measurements of adsorbate reduction, the time evolution of conduction band carriers was determined using sum frequency up conversion of the recombination luminescence. In addition, the formation and decay of surface trapped carriers was monitored using near infrared transient absorption. Comparing the time scale for photoreduction with the relaxation kinetics of mobile and trapped charge carriers indicates that short lived mobile carriers rather than longer lived surface trapped carriers dominate interfacial charge transfer in this system.

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Using near-infrared spectroscopy and differential adsorption bed method to study adsorption kinetics of orthoxylene on silica gel

Talanta ◽

10.1016/j.talanta.2008.04.021 ◽

2008 ◽

Vol 76 (4) ◽

pp. 752-757 ◽

Cited By ~ 2

Author(s):

Q HAN ◽

H WU ◽

C CAI ◽

L TANG ◽

R YU

Keyword(s):

Infrared Spectroscopy ◽

Silica Gel ◽

Near Infrared Spectroscopy ◽

Adsorption Kinetics ◽

Near Infrared ◽

Differential Adsorption Bed ◽

Kinetics Of

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Abstract 14822: Impact of Proportional Assist Ventilation on Skeletal Muscle Reoxygenation and Central Hemodynamic During Constant Work Rate Exercise in Chronic Heart Failure

Circulation ◽

10.1161/circ.130.suppl_2.14822 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Audrey Borghi-Silva ◽

Luiz Eduardo Nery ◽

Dirceu R de Almeida ◽

Jose Alberto Neder

Keyword(s):

Heart Failure ◽

Skeletal Muscle ◽

Cardiac Output ◽

Infrared Spectroscopy ◽

Chronic Heart Failure ◽

High Intensity ◽

Near Infrared ◽

Work Rate ◽

Constant Work Rate ◽

Kinetics Of

Introduction: Progressive chronic heart failure slows the recovery of microvascular oxygen delivery and utilization, which produce deleterious implications to exercise capacity. Respiratory muscle unloading can enhance the responses to exercise thereby allowing a closer matching between skeletal muscle oxygen delivery and utilization in patients with chronic heart failure (CHF). Hypothesis: We reasoned that noninvasive ventilation administered by proportional assisted ventilation (PAV) could accelerate skeletal muscle reoxygenation after high intensity exercise in CHF humans. To test this hypothesis, we conducted a study with 12 patients with stable CHF who were randomized to receive PAV or sham ventilation during high-intensity constant work exercise and compared the effects of these interventions on oxygen pulmonary (O2p), cardiac output and [[Unable to Display Character: ∆]][deoxi-Hb+Mb] off kinetics. Methods: Twelve patients with CHF (NYHA class II and III and left ventricle ejection fraction= 26±9%) underwent two high-intensity, constant-work rate (80% peak) cycle ergometer tests receiving PAV or sham ventilation. Off-exercise kinetics of the primary component of oxygen uptake, an index of fractional oxygen extraction by near infrared spectroscopy (~[[Unable to Display Character: ∆]][deoxy-Hb+Mb]) in the vastus lateralis) and cardiac output (QT) by impedance cardiography were assessed. Results: PAV significantly accelerated the recovery of O2p when compared with sham τ = 56±22 vs. 77±42s, respectively, p<0.05). Interestingly, PAV was associated with faster fractional O2 extraction (~[[Unable to Display Character: ∆]][deoxy-Hb+Mb] by near-infrared spectroscopy) (τ= 31±19 vs. 42±22s, respectively, p<0.05) . In addition, kinetics of QT were significantly faster with PAV than sham (τ = 39±22 vs. 78±46s, respectively, p<0.05). Conclusions: These data indicate that PAV has beneficial effects on recovery of muscle metabolism and central hemodynamics after high-intensity exercise in CHF patients. Financial Support: FAPESP 2009-01842-0

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Visualizing Chemical Compositions and Kinetics of Sol−Gel by Near-Infrared Multispectral Imaging Technique

Analytical Chemistry ◽

10.1021/ac011194j ◽

2002 ◽

Vol 74 (7) ◽

pp. 1604-1610 ◽

Cited By ~ 7

Author(s):

Chieu D. Tran ◽

Mario Politi

Keyword(s):

Near Infrared ◽

Multispectral Imaging ◽

Imaging Technique ◽

Sol Gel ◽

Chemical Compositions ◽

Kinetics Of

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Kinetics of Photobleaching of β-Carotene in Chloroform and Formation of Transient Carotenoid Species Absorbing in the Near Infrared

Free Radical Research ◽

10.3109/10715769609149058 ◽

1996 ◽

Vol 25 (4) ◽

pp. 355-368 ◽

Cited By ~ 46

Author(s):

Alan Mortensen ◽

Leif H. Skibsted

Keyword(s):

Near Infrared ◽

Kinetics Of ◽

Β Carotene

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Kinetics of muscle deoxygenation are accelerated at the onset of heavy-intensity exercise in patients with COPD: relationship to central cardiovascular dynamics

Journal of Applied Physiology ◽

10.1152/japplphysiol.01364.2007 ◽

2008 ◽

Vol 104 (5) ◽

pp. 1341-1350 ◽

Cited By ~ 70

Author(s):

Gaspar R. Chiappa ◽

Audrey Borghi-Silva ◽

Leonardo F. Ferreira ◽

Claúdia Carrascosa ◽

Cristino Carneiro Oliveira ◽

...

Keyword(s):

Near Infrared ◽

Exercise Intolerance ◽

Chronic Obstructive ◽

Regression Equations ◽

Dynamic Matching ◽

Muscle Deoxygenation ◽

Dynamic Relationship ◽

Copd Patients ◽

Kinetics Of ◽

Severe Copd

Patients with chronic obstructive pulmonary disease (COPD) have slowed pulmonary O2 uptake (V̇o2p) kinetics during exercise, which may stem from inadequate muscle O2 delivery. However, it is currently unknown how COPD impacts the dynamic relationship between systemic and microvascular O2 delivery to uptake during exercise. We tested the hypothesis that, along with slowed V̇o2p kinetics, COPD patients have faster dynamics of muscle deoxygenation, but slower kinetics of cardiac output (Q̇t) following the onset of heavy-intensity exercise. We measured V̇o2p, Q̇t (impedance cardiography), and muscle deoxygenation (near-infrared spectroscopy) during heavy-intensity exercise performed to the limit of tolerance by 10 patients with moderate-to-severe COPD and 11 age-matched sedentary controls. Variables were analyzed by standard nonlinear regression equations. Time to exercise intolerance was significantly ( P < 0.05) lower in patients and related to the kinetics of V̇o2p ( r = −0.70; P < 0.05). Compared with controls, COPD patients displayed slower kinetics of V̇o2p (42 ± 13 vs. 73 ± 24 s) and Q̇t (67 ± 11 vs. 96 ± 32 s), and faster overall kinetics of muscle deoxy-Hb (19.9 ± 2.4 vs. 16.5 ± 3.4 s). Consequently, the time constant ratio of O2 uptake to mean response time of deoxy-Hb concentration was significantly greater in patients, suggesting a slower kinetics of microvascular O2 delivery. In conclusion, our data show that patients with moderate-to-severe COPD have impaired central and peripheral cardiovascular adjustments following the onset of heavy-intensity exercise. These cardiocirculatory disturbances negatively impact the dynamic matching of O2 delivery and utilization and may contribute to the slower V̇o2p kinetics compared with age-matched controls.

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