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1.
J Knee Surg ; 2024 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-38788758

RESUMEN

The purpose of this study was to evaluate outcomes of late manipulation under anesthesia (MUA) for stiffness performed from ≥12 weeks to more than a year after primary total knee arthroplasty (TKA). A total of 152 patients receiving MUA ≥12 weeks after primary TKA from 2014 to 2021 were reviewed. The primary outcome measured was change in range of motion (ROM). We tracked intraoperative complications and the need for repeat MUA or open procedure for continued stiffness after initial MUA. Three subgroups were analyzed: Group 1 included 58 knees between 12 weeks and 6 months after TKA, Group 2 included 44 knees between 6 and 12 months after TKA, and Group 3 included 50 knees ≥12 months after TKA. Analysis included descriptive statistics and univariate analysis, with α <0.05. Groups 1 to 3 all significantly increased their overall ROM by 20.9, 19.2, and 22.0 degrees, respectively. All groups significantly increased their flexion and extension from preoperatively. Group 1 had one intraoperative supracondylar femur fracture (1.7%) requiring open reduction and internal fixation, and five patients required repeat MUA or open procedure (8.6%). Group 2 had no intraoperative fractures, and five patients required repeat MUA or open procedure (11.4%). Group 3 had one intraoperative tibial tubercle avulsion fracture managed conservatively (2.0%) and one repeat MUA (2.0%). Late MUA resulted in significantly improved ROM in all groups. ROM improved more as the time from index TKA increased, although statistically insignificant. Repeat MUA or open procedure rate decreased with MUA ≥12 months from TKA, although statistically insignificant. The overall intraoperative fracture risk was 1.3%.

2.
J Surg Orthop Adv ; 33(1): 5-9, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38815070

RESUMEN

The objective of this study was to determine if preoperative patient characteristics have an effect on pain and function after primary arthroscopic rotator cuff repair. Seventy-five arthroscopic primary rotator cuff repairs with at least 2 years of follow-up were identified. Studied variables were preoperative tobacco, opioid, and alcohol use; obesity; mood disorders; disability claim; and Workers' Compensation status. Outcome measures included visual analog pain scores, American Shoulder and Elbow Surgeons (ASES) scores, Single Assessment Numeric Evaluation (SANE) scores, range of motion, and strength. Preoperative smoking was significantly associated with worse pain (p = 0.009), ASES (p = 0.004), and SANE (p = 0.011) scores. Opioid use showed no statistically significant difference in pain or functional scores. Alcohol use did predict improved ASES scores at long-term follow-up (p = 0.046). The other variables were not associated with inferior outcomes. Smoking and preoperative opioid use represent modifiable risk factors that can be corrected before surgery to optimize outcomes. (Journal of Surgical Orthopaedic Advances 33(1):005-009, 2024).


Asunto(s)
Artroscopía , Lesiones del Manguito de los Rotadores , Fumar , Humanos , Masculino , Femenino , Persona de Mediana Edad , Factores de Riesgo , Lesiones del Manguito de los Rotadores/cirugía , Fumar/epidemiología , Anciano , Rango del Movimiento Articular , Dimensión del Dolor , Analgésicos Opioides/uso terapéutico , Consumo de Bebidas Alcohólicas/epidemiología , Adulto , Estudios Retrospectivos , Resultado del Tratamiento , Obesidad/complicaciones , Indemnización para Trabajadores , Dolor Postoperatorio/tratamiento farmacológico
4.
RSC Adv ; 14(12): 8251-8259, 2024 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-38469183

RESUMEN

CoMoO4 is a promising battery-type supercapacitor electrode material that can offer relatively high storage capacity and cycle stability. In this work, we investigate the role of the crystalline phase of CoMoO4 in determining these performance parameters. The hydrate phase of CoMoO4 was synthesized on a nickel foam substrate via hydrothermal reaction with subsequent annealing under an inert atmosphere leading to the formation of the ß-phase CoMoO4. Similar nanoplate morphologies were observed in all of the samples. The hydrate-phase CoMoO4 demonstrates larger specific capacity than the annealed ß-phase CoMoO4. Besides, the samples synthesized at lower temperatures have better rate capability than the sample annealed at higher temperatures. However, the hydrate phase had worse long-term stability compared to the ß-phase samples.

5.
ACS Catal ; 13(21): 14189-14198, 2023 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-37942270

RESUMEN

Supported bimetallic catalysts commonly exhibit higher rates of reaction compared to their monometallic counterparts, but the origin of these enhancements is often poorly defined. The recent discovery that cooperative redox enhancement effects in Au-Pd systems promote bimetallic catalysis in thermochemical oxidation is an important development in this field. This effect aligns two important research fields, thermo- and electrocatalysis, but questions relating to the generality and origin of the effect remain. Here, we demonstrate that these effects can be observed in reactions over a range of bimetal combinations and reveal the origin using a combination of electrochemical and material characterization. We disclose that the observed activity enhancement in thermochemical systems is a result of the electrochemical polarization of two disparate catalytic sites. This forms an alternative operating potential for a given bimetallic system that increases the driving force of each of the composite half reactions in oxidative dehydrogenation. We therefore uncover the physicochemical descriptors that dictate whether these enhancement effects will be exhibited by a particular combination of supported metal catalysts and determine the magnitude of the effect.

6.
ACS Appl Nano Mater ; 6(9): 7668-7678, 2023 May 12.
Artículo en Inglés | MEDLINE | ID: mdl-37304254

RESUMEN

The enzymatic production of hydrogen sulfide (H2S) from cysteine in various metabolic processes has been exploited as an intrinsically "green" and sustainable mode for the aqueous biomineralization of functional metal sulfide quantum dots (QDs). Yet, the reliance on proteinaceous enzymes tends to limit the efficacy of the synthesis to physiological temperature and pH, with implications for QD functionality, stability, and tunability (i.e., particle size and composition). Inspired by a secondary non-enzymatic biochemical cycle that is responsible for basal H2S production in mammalian systems, we establish how iron(III)- and vitamin B6 (pyridoxal phosphate, PLP)-catalyzed decomposition of cysteine can be harnessed for the aqueous synthesis of size-tunable QDs, demonstrated here for CdS, within an expanded temperature, pH, and compositional space. Rates of H2S production by this non-enzymatic biochemical process are sufficient for the nucleation and growth of CdS QDs within buffered solutions of cadmium acetate. Ultimately, the simplicity, demonstrated robustness, and tunability of the previously unexploited H2S-producing biochemical cycle help establish its promise as a versatile platform for the benign, sustainable synthesis of an even wider range of functional metal sulfide nanomaterials for optoelectronic applications.

7.
J Mater Chem B ; 10(24): 4529-4545, 2022 06 22.
Artículo en Inglés | MEDLINE | ID: mdl-35608268

RESUMEN

The development of high quality, non-toxic (i.e., heavy-metal-free), and functional quantum dots (QDs) via 'green' and scalable synthesis routes is critical for realizing truly sustainable QD-based solutions to diverse technological challenges. Herein, we demonstrate the low-temperature all-aqueous-phase synthesis of silver indium sulfide/zinc (AIS/Zn) QDs with a process initiated by the biomineralization of highly crystalline indium sulfide nanocrystals, and followed by the sequential staging of Ag+ cation exchange and Zn2+ addition directly within the biomineralization media without any intermediate product purification. Therein, we exploit solution phase cation concentration, the duration of incubation in the presence of In2S3 precursor nanocrystals, and the subsequent addition of Zn2+ as facile handles under biomineralization conditions for controlling QD composition, tuning optical properties, and improving the photoluminescence quantum yield of the AIS/Zn product. We demonstrate how engineering biomineralization for the synthesis of intrinsically hydrophilic and thus readily functionalizable AIS/Zn QDs with a quantum yield of 18% offers a 'green' and non-toxic materials platform for targeted bioimaging in sensitive cellular systems. Ultimately, the decoupling of synthetic steps helps unravel the complexities of ion exchange-based synthesis within the biomineralization platform, enabling its adaptation for the sustainable synthesis of 'green', compositionally diverse QDs.


Asunto(s)
Puntos Cuánticos , Biomineralización , Cationes , Indio/química , Puntos Cuánticos/química , Sulfuros/química , Temperatura , Agua/química , Zinc/química
8.
J Pediatr Urol ; 18(6): 804-811, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-35501240

RESUMEN

OBJECTIVES: Ureteral stents are commonly used during pyeloplasty to ensure drainage and anastomotic healing. Antibiotic prophylaxis is often used due to concerns for urinary tract infection (UTI). Although many surgeons prescribe prophylactic antibiotics following pyeloplasty, practices vary widely due to lack of clear evidence-based guidelines. We hypothesize that the rate of stent UTI does not significantly vary between children who receive antibiotics and those who do not. METHODS: We reviewed the medical records of 741 patients undergoing pyeloplasty between January 2010 and July 2018 across seven institutions. Exclusion criteria were: age older than 22 years, no stent placed, externalized stents used, and incomplete records. Surgical approach, age, antibiotic use, stent duration, Foley duration, and urine culture results were recorded. Patients were categorized into two groups, those younger than four years of age and those four years and older as proxy for likely diaper use. Univariate logistic regression was conducted to identify variables associated with UTI. Multivariable backward stepwise logistic regression was used to identify the best model with Akaike information criterion as model selection criteria. The selected model was used to calculate odds ratios and 95% confidence intervals summarizing the association between prophylactic antibiotics and stent UTI while controlling for age, gender, and intra-operative urine cultures. RESULTS: 672 patients were included; 338 received antibiotic prophylaxis and 334 did not. These groups differed in mean age (3.91 vs. 6.91 years, P < .001), mean stent duration (38.5 vs. 35.32 days, P < .001), and surgical approach (53.25% vs. 32.04% open vs. laparoscopic, P < .001). The incidence of stent UTI was low overall (7.59%) and similar in both groups: 31/338 (9.17%) in the prophylaxis group and 20/334 (5.99%) in the non-prophylaxis group (P = .119). Although female gender, likely diaper use, and positive intra-operative urine culture were each associated with significantly higher odds of stent UTI, prophylactic antibiotic use was not associated with significant reduction in stent UTI in any of these groups. Surgical approach, stent duration, and Foley duration were not associated with stent UTI. CONCLUSION: Incidence of stent UTI is low overall following pyeloplasty. Prophylactic antibiotics are not associated with lower rates of stent UTI following pyeloplasty even after controlling for risk factors of female gender, likely diaper use, and positive intra-operative urine culture. Routine administration of prophylactic antibiotics after pyeloplasty does not appear to be beneficial, and may be best reserved for those with multiple risk factors for UTI.


Asunto(s)
Laparoscopía , Uréter , Infecciones Urinarias , Humanos , Niño , Femenino , Adulto Joven , Adulto , Uréter/cirugía , Procedimientos Quirúrgicos Urológicos/métodos , Stents/efectos adversos , Laparoscopía/efectos adversos , Infecciones Urinarias/etiología , Infecciones Urinarias/prevención & control , Infecciones Urinarias/epidemiología , Antibacterianos/uso terapéutico , Estudios Retrospectivos
9.
Orthop Clin North Am ; 52(3): 201-208, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34053565

RESUMEN

Based on a series of 407 outpatient total hip arthroplasties performed by a single surgeon, a standardized protocol for blood loss management in outpatient arthroplasty was developed consisting of a presurgical hematocrit of greater than 36%, administration of tranexamic acid, prophylactic introduction of albumin, hypotensive epidural anesthesia, monopolar electrocautery, and bipolar sealer. This protocol uses techniques that alone are not novel but together create a standardized and reproducible pathway that when implemented can increase the safety of outpatient hip arthroplasty.


Asunto(s)
Procedimientos Quirúrgicos Ambulatorios/métodos , Artroplastia de Reemplazo de Cadera/métodos , Pérdida de Sangre Quirúrgica/prevención & control , Adulto , Anciano , Procedimientos Quirúrgicos Ambulatorios/normas , Antifibrinolíticos/uso terapéutico , Artroplastia de Reemplazo de Cadera/normas , Electrocoagulación , Femenino , Humanos , Masculino , Persona de Mediana Edad , Ácido Tranexámico/uso terapéutico , Adulto Joven
10.
Telemed J E Health ; 27(2): 213-217, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-32539570

RESUMEN

Introduction: Telemedicine allows health care professionals to diagnose and treat patients remotely. Enuresis is one of the most common chronic problems in childhood and specialized care can be limited. Utilization of telemedicine in this setting has not been previously analyzed. Materials and Methods: This study's aim is to evaluate the feasibility and effectiveness of telemedicine follow-up treatment of enuresis compared with traditional follow-up at our institution. A retrospective review of patients treated for nocturnal enuresis with either telemedicine (Group 1) or traditional (Group2) follow-up care was conducted. Patients, aged 5-18 years, treated for enuresis between July 2016 and December 2017 were included. Patients with confounding disease were excluded. Resolution of enuresis was the primary outcome as categorized by the International Children's Continence Society standards. Results: Seventy-seven (n = 77) patients met inclusion criteria with 23 patients in Group 1 and 54 patients in Group 2. Two patients in each group were lost to follow-up and 61.9% in Group 1 and 48.1% in Group 2 responded to treatment. The average age for both groups was 9.2 years. Patients in Group 1 averaged four appointments per patient and patients in Group 2 averaged 3.04 appointments per patient. Telemedicine follow-up patients missed fewer appointments (0.14) than patients with traditional follow-up (0.5) (p-value = 0.016). Thirteen of 21 patients (61.9%) responded to treatment in Group 1 (7 partial and 6 complete responders) as compared with 25 of 52 patients (48.1%) responding to treatment in Group 2 (8 partial and 17 complete responders) (p = 0.22). Of patients in Group 1, 87% reported they would use telemedicine again. Conclusions: Telemedicine follow-up of patients with enuresis demonstrated comparable effectiveness. Most patient families demonstrate a favorable opinion of using telemedicine again for this problem. Further research to understand the efficacy and benefits of telemedicine in this setting is needed.


Asunto(s)
Enuresis Nocturna , Telemedicina , Incontinencia Urinaria , Adolescente , Niño , Preescolar , Estudios de Seguimiento , Humanos , Estudios Retrospectivos
11.
ACS Appl Mater Interfaces ; 12(38): 42773-42780, 2020 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-32865390

RESUMEN

Nanocomposite photocatalysts offer a promising route to efficient and clean hydrogen production. However, the multistep, high-temperature, solvent-based syntheses typically utilized to prepare these photocatalysts can limit their scalability and sustainability. Biosynthetic routes to produce functional nanomaterials occur at room temperature and in aqueous conditions, but typically do not produce high-performance materials. We have developed a method to produce a highly efficient hydrogen evolution photocatalyst consisting of CdS quantum dots (QDs) supported on reduced graphene oxide (rGO) via enzyme-based syntheses combined with tuned ligand exchange-mediated self-assembly. All preparation steps are carried out in an aqueous environment at ambient temperature. Size-controlled CdS QDs and rGO are prepared through enzyme-mediated turnover of l-cysteine to HS- in aqueous solutions of Cd-acetate and graphene oxide, respectively. Exchange of cysteamine for the native l-cysteine ligand capping the CdS QDs drives self-assembly of the now positively charged cysteamine-capped CdS (CdS/CA) onto negatively charged rGO. The use of this short linker molecule additionally enables efficient charge transfer from CdS to rGO, increasing exciton lifetime and, subsequently, photocatalytic activity. The visible-light hydrogen evolution rate of the resulting CdS/CA/rGO photocatalyst is 3300 µmol h-1 g-1. This represents, to our knowledge, one of the highest reported rates for a CdS/rGO nanocomposite photocatalyst, irrespective of the synthesis method.

12.
Orthop Clin North Am ; 51(2): 235-239, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32138861

RESUMEN

To determine if orthopedic surgeons are more efficient than nonsurgical providers at care of operative injuries in walk-in clinics, patients in a walk-in clinic for evaluation of acute injury who subsequently had surgical treatment of isolated distal radial fracture were compared based on whether the initial visit was with a surgical or nonsurgical provider. Initial evaluation in a walk-in orthopedic clinic setting versus a conventional hand surgeon's clinic was associated with longer delay between initial evaluation and surgical treatment, but this difference may not be significant. Evaluation by a nonsurgical provider was not associated with increased duration to definitive treatment.


Asunto(s)
Fracturas del Radio/cirugía , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Atención Ambulatoria , Instituciones de Atención Ambulatoria , Femenino , Fijación Interna de Fracturas , Curación de Fractura , Humanos , Masculino , Persona de Mediana Edad , Fracturas del Radio/terapia , Tiempo de Tratamiento , Adulto Joven
13.
ACS Appl Mater Interfaces ; 11(49): 45656-45664, 2019 Dec 11.
Artículo en Inglés | MEDLINE | ID: mdl-31730749

RESUMEN

CuZnSnS (CZTS) quantum dots (QDs) have potential application in quantum dot sensitized solar cells (QDSSCs); however, traditional synthesis approaches typically require elevated temperatures, expensive precursors, and organic solvents that can hinder large-scale application. Herein we develop and utilize an enzymatic, aqueous-phase, ambient temperature route to prepare CZTS nanocrystals with good compositional control. Nanoparticle synthesis occurs in a minimal buffered solution containing only the enzyme, metal chloride and acetate salts, and l-cysteine as a capping agent and sulfur source. Beyond isolated nanocrystal synthesis, we further demonstrate biomineralization of these particles within a preformed mesoporous TiO2 anode template where the formed nanocrystals bind to the TiO2 surface. This in situ biomineralization approach facilitates enhanced distribution of the nanocrystals in the anode and, through this, enhanced QDSSC performance.

14.
Nanoscale ; 10(44): 20785-20795, 2018 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-30402624

RESUMEN

Traditional quantum dot synthesis techniques rely on the separation of nucleation and growth to control nanocrystal size. However, the same goal can be achieved through slow and continuous introduction of reactive precursors to keep the growth mechanism in the size focusing regime throughout synthesis. In this work, we demonstrate the efficacy of this approach within the framework of functional material biomineralization where, despite simultaneous nucleation and growth of particles, this growth mechanism enables size-controlled nanocrystal synthesis. Herein, the single enzyme cystathionine γ-lyase (CSE) is utilized to biomineralize CdS nanocrystals via the slow, but continuous turnover of the amino acid l-cysteine to produce H2S. Nanocrystal nucleation and growth theories confirm that consistent addition of monomers will result in a high supersaturation term, driving the nanocrystal growth mechanism into the size focusing regime. We further confirm this theory by mimicking biomineralization via chemical routes and demonstrate the influence of varying supersaturation, to further control the average nanocrystal size. Finally, altering the chelation strength of the capping agent l-cysteine is found to play a key role in balancing nanocrystal growth in solution and long-term stability.

15.
Chemphyschem ; 18(1): 59-63, 2017 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-27862796

RESUMEN

Derivatives of 9-(2,2,2-triphenylethylidene)-fluorene (TEF) undergo E/Z photoisomerization and are candidates for light-powered molecular actuators and switches. The 2-substituted derivatives bearing an amino group (ATEF) or a dimethylamino group (DTEF) are weakly photoactive in the absence of acids, but protonation increases photoisomerization quantum yields by factors of 30-60. Such compounds may be useful for incorporation into pH-switchable photoactive devices.

16.
Chemistry ; 22(32): 11291-302, 2016 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-27363530

RESUMEN

The synthesis, spectral and structural characterization, and photoisomerization of a family of 2-substituted dibenzofulvene molecular actuators based on (2,2,2-triphenylethylidene)fluorene (TEF) are reported. The 2-substituted species investigated are nitro (NTEF), cyano (CTEF), and iodo (ITEF). X-ray structures of these three compounds and three intermediates were determined to assign alkene configuration and investigate the effects of the 2-substituents on steric gearing. The addition-elimination reaction of Z-9 with trityl anion to form Z-10 proceeded with complete retention of configuration. Rates of photoisomerization were measured at irradiation wavelengths between 266-355 nm in acetonitrile/dioxane solutions at room temperature. Photoisomerization quantum yields (φ) were calculated by means of a mathematical model that accounts for a certain degree of photodecomposition in the cases of CTEF and ITEF. Quantum yields vary significantly with substituent, having maximum values of φ=0.26 for NTEF, 0.39 for CTEF, and 0.50 for ITEF. NTEF is photochemically robust and has a large quantum yield for photoisomerization in the near-UV, making it a particularly promising drive rotor moiety for light-powered molecular devices.

17.
J Emerg Med ; 48(1): 39-42, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25453859

RESUMEN

BACKGROUND: Baptisia is commonly found in residential gardens as an ornamental plant, in municipal "rain gardens" for water control, as well as in native and restored prairie habitat. Cytisine, an alkaloid with nicotinic acetylcholine receptor agonist properties, is a component of Baptisia. CASE REPORT: Two patients poisoned after simultaneously ingesting Baptisia plant material are presented. In addition to findings of generalized nicotinic agonist toxicity, including generalized weakness and gastrointestinal symptoms, profound ataxia was present in both, consistent with recently described nicotinic subunit activity in the cerebellum. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Baptisia, a native prairie plant commonly found in restored prairie habitats and public spaces, has striking "look-alike" characteristics, in its immature state, to asparagus. As future exposures by foraging citizens will be likely, awareness of this relationship and the toxic manifestations of cytisine will be useful.


Asunto(s)
Alcaloides/envenenamiento , Fabaceae/envenenamiento , Agonistas Nicotínicos/envenenamiento , Anciano de 80 o más Años , Asparagus , Ataxia/etiología , Azocinas/envenenamiento , Femenino , Humanos , Persona de Mediana Edad , Debilidad Muscular/etiología , Náusea/etiología , Quinolizinas/envenenamiento , Vómitos/etiología
18.
Case Rep Orthop ; 2015: 262187, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26881160

RESUMEN

Posterolateral rotatory instability is a relatively uncommon cause of unstable total knee arthroplasty (TKA). In most cases, surgical treatment requires revision TKA into a more constrained design or thicker polyethylene liner. We present a case of a patient with unstable TKA who remained unstable after increasing thickness of the polyethylene liner and undergoing more constrained TKA. After several revision surgeries, the patient was still unstable. Posterolateral corner reconstruction with a fibular-based technique using a tibialis anterior allograft was performed. At 1-year follow-up, the patient was stable and asymptomatic and with excellent function. A soft-tissue procedure only (fibular-based posterolateral corner reconstruction) can be effective at restoring posterolateral rotatory stability in a patient with persistent instability after revision TKA.

19.
J Phys Chem A ; 115(4): 410-8, 2011 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-21210692

RESUMEN

A normal-incidence geometry, polarization-resolved cavity ring-down spectroscopy technique (polarized NICRDS) is described to probe the polarized absorbance of surface-adsorbed thin films and short-path length liquid samples. The technique is demonstrated by a kinetic study of the photochromic behavior of the spiropyran dye 6,8-dibromo-1', 3'-dihydro-1', 3', 3'-trimethylspiro[2H-1-benzopyran-2, 2'-(2H)-indole]. The technique is shown potentially to have monolayer coverage sensitivity and can measure the angular orientation distribution of analyte molecules. The photochromic kinetics of 6,8-dibromoBIPS in toluene solution were qualitatively consistent with a previous study of this molecule using conventional absorption spectroscopy. The absorption polarizations and slow ring-closing kinetics measured in a thin poly(methyl methacrylate) film are consistent with a strong interaction of the spiropyran and merocyanine forms with the polymer matrix.

20.
J Phys Chem A ; 115(4): 419-27, 2011 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-21210693

RESUMEN

The molecule 2-nitro-9-(2,2,2-triphenylethylidene)fluorene (NTEF) was studied as a potential light-driven molecular motor. Absorption at 355 nm causes a reversible spatial reorientation of the angular distribution of the dibenzofulvene rotor moiety of NTEF when immobilized in a poly(methyl methacrylate) (PMMA) matrix adsorbed on a fused silica surface in air at room temperature. The photoreorientation dynamics was probed by polarized normal incidence cavity ringdown spectroscopy (NICRDS) when the matrix was irradiated by linearly polarized "drive" light. Polarized drive irradiation at 355 nm creates a "hole" in the angular distribution of the molecular transition dipoles. Changing the polarization of the drive beam refills the hole, creating a new hole. A stochastic model was fitted to the experimental hole burning measurements to obtain a photoreorientation quantum yield (Φ(reorient) = 0.014). The photoreorientation process appears to be driven by photoisomerization of the exocyclic dibenzofulvene double bond of NTEF.

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