Contribution of Different Impairments to Restricted Knee Flexion during Gait in Individuals with Cerebral Palsy.

The coexistence of overlapping impairments modulates the knee pattern in the swing phase of walking in children with cerebral palsy (CP). The impact and contribution of each impairment to the reduction of knee range-of-motion is unknown. The aim of the study was to establish the gradation of the impact of individual coexisting impairments on the knee flexion range-of-motion. Passive range-of-motion, selective motor control, strength, and spasticity from 132 patients (Male = 76, Female = 56, age:11 ± 4 years) with spastic CP were tested with clinical tools. Knee flexion range-of-motion at terminal stance, pre-swing, and initial swing phases were assessed by gait analysis. Hypertonia (ß = −5.75) and weakness (ß = 2.76) of knee extensors were associated with lower range of knee flexion (R2 = 0.0801, F = 11.0963, p < 0.0001). The predictive factors (R2 = 0.0744, F = 7.2135, p < 0.0001) were strength (ß = 4.04) and spasticity (ß = −2.74) of knee extensors and strength of hip flexors (ß = −2.01); in swing those were knee extensors hypertonia (ß = −2.55) and passive range of flexion (ß = 0.16) (R2 = 0.0398, F = 3.4010, p = 0.01). Hypertonia of knee extensors has the strongest impact on knee flexion range-of-motion; secondary is the strength of knee extensors. The knee extensors strength with knee extensors hypertonia and strength of hip flexors contributes in stance. Knee extensors hypertonia with passive knee flexion range-of-motion contributes in swing.

Effects of Robot-Assisted Therapy on Gait Parameters in Pediatric Patients With Spastic Cerebral Palsy.

Background: Gait dysfunction is a crucial factor that restricts independence and quality of life in children with cerebral palsy (CP). Gait training based on robotic-assisted therapy (RAT) is widely used, but information about effectiveness and ideal patient profile is not sufficient. Aim of this study was to assess the effect of RAT on gait parameters in spastic children with CP, and to determine whether changes in gait parameters are different among patients on different ambulatory levels. Method: A total of 26 children with bilateral spastic CP were divided into two groups based on their functional ability: non-assisted ambulator (NAS) or assisted ambulator (AS); and underwent a RAT program (30 training sessions of RAT during 10 weeks). Gait analysis was performed: before the therapy (t1), right after (t2), and 6 weeks later (t3). Results: No significant changes in spatiotemporal parameters or gait deviation index at t2 or t3. Double support symmetry significantly improved (t1 vs. t3, p = 0.03) for the whole group (NAS + AS). Walking speed symmetry significantly improved (t2 vs. t3, p = 0.02) for group AS. Conclusion: RAT based on our protocol did not change spatiotemporal parameters and kinematics of walking except limited improvement in some aspects of gait symmetry. We did not find differences in changes in selected objective gait parameters among children with CP in different ambulatory levels.

Control of the Photo-Isomerization Mechanism in 3H-Naphthopyrans to Prevent Formation of Unwanted Long-Lived Photoproducts.

In the photochromic reactions of 3H-naphthopyrans, two colored isomers TC (transoid-cis) and TT (transoid-trans) are formed. In terms of optimized photo-switchable materials, synthetic efforts are nowadays evolving toward developing 3H-naphthopyran derivatives that would not be able to photoproduce the long-living transoid-trans, TT, photoproduct. The substitution with a methoxy group at position 10 results in significant reduction of the TT isomer formation yield. The TC photophysics responsible for TT suppression were revealed here using a combination of multi-scale time resolved absorption UV-vis spectroscopy and ab initio calculations. The substitution changes the TC excited-state potential energy landscape, the bicycle-pedal isomerization path is favored over the rotation around a single double bond. The bicycle-pedal path is aborted in halfway to TT formation due to S1→S0 internal conversion populating back the TC species in the ground electronic state. This is validated by a shorter TC S1 state lifetime for methoxy derivative in comparison to that of the parent-unsubstituted compound (0.47 ± 0.05 ps vs. 0.87 ± 0.09 ps) in cyclohexane.

Thermal lens with passively tuned focal length formed in a photochromic material.

A new, to the best of our knowledge, way of tuning the focal length of a thermal lens is presented. The thermal lens is formed in a photochromic thermo-optical material, through illumination of the material by a heating laser beam of constant power. The tunability of the lens is achieved by changing the absorption coefficient of the thermo-optical material at the heating laser beam wavelength. This change is obtained by modifying the intensity of the additional, flat in profile, light of a wavelength different than that of the heating laser beam. The change in intensity of this light may follow from the effects of external factors, as, e.g., decrease in daylight intensity. Therefore, the lens may be considered as a passive auto-tuning lens, with focal length auto-adjusting to the external illumination.

Ultrafast Dynamics of the Transoid-cis Isomer Formed in Photochromic Reaction from 3H-Naphthopyran.

Recent efforts in designing new 3H-naphthopyran derivatives have been focused on efficient coloration process with a short fading time of the colored transoid-cis TC isomer. It is desirable to avoid photoisomerization of TC leading to transoid-trans TT isomers in the photoreaction. Long lifetime of TT can hamper fast applications such as dynamic holographic materials and molecular actuators, the residual color is one of the serious issues for photochromic lenses. Herein we characterize the photophysical and photochemical channels of TC excited state deactivation competing with the unwanted TC→TT isomerization process. Transient absorption spectroscopy reveals a very short lifetime of the singlet excited TC (≈0.8 ps) and its deactivation channels as S1 →S0 internal conversion (major), intersystem crossing S1 →T1 , pyran ring formation, photoenolization and TC→TT isomerization. Computations support the S1 →S0 and T1 →S0 channels as responsible for photostabilization of the TC form.

Photochromic reaction in 3H-naphthopyrans studied by vibrational spectroscopy and quantum chemical calculations.

Structural details on the species involved in the photochromic reaction of 3H-naphthopyrans in solution have been formerly determined using NMR spectroscopy. Herein we show that at room temperature time-resolved FT-IR spectroscopy is a simple and efficient tool for structural characterization of colored species generated upon continuous UV light irradiation of the model compound 3H-naphthopyran: 3,3-diphenyl-3H-naphtho[2,1-b]pyran. In solution and in the polymer matrix phase, a colored species transoid-cis is formed after a single-photon excitation process, while transoid-trans is a secondary long-lived photoproduct generated after two-step excitation involving two photons. Understanding the reaction mechanism leading to long-lived colored species can help with the design of new 3H-naphthopyran derivatives structurally optimized for making a photochromic reaction free from transoid-trans products, which is often important for applications. Ab initio calculations show that photoinduced ring-opening followed by isomerization occurs on a multidimensional potential-energy surface. The barriers separating the considered isomeric forms, both in the ground and in the excited state, help to interpret the step-by-step dynamics of the photoprocesses. The system is composed of a variety of ground state equilibrium forms. Each of them is characterized by fast excited-state deactivation pathways which may drive the system through different conical intersection regions.

Disclosing Whole Reaction Pathways of Photochromic 3H-Naphthopyrans with Fast Color Fading.

Instantaneous coloration with large absorbance and quick color fading in the dark are desired properties for thermally reversible photochromic compounds. In the case of naphthopyran derivatives, which have been employed to commercial ophthalmic lenses, the quick color fading has been recently achieved by suppression of the generation of the transoid-trans (TT) form by steric hindrance of bulky substituents. However, there are still open questions whether the steric hindrance decreases the photochromic reaction efficiency, which is a crucial problem for industrial applications. Herein, we apply a wide range of electronic and vibrational time-resolved spectroscopies and reveal that the photochromic reaction yields of the naphthopyrans with bulky substituents are almost comparable (∼0.7) to that of nonsubstituted naphthopyran. The suppression of the formation of the TT form and the effect of solvent polarity on the photodynamics are systematically investigated. These findings are important for fundamental photochemistry and developing naphthopyran-based optimal photofunctional materials.