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1.
Int Orthop ; 47(9): 2327-2336, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37477682

RESUMEN

PURPOSE: Complex bicondylar tibial plateau fracture (TPF) has always been a tricky problem for surgeons. We created a novel external device used intraoperatively consisting of Kirschner wires, and combined with minimally invasive plate oseoynthesis (MIPO) technique to treat complex bicondylar TPFs, and the clinical effect and feasibility were further evaluated. METHODS: From March 2016 to February 2021, 49 cases (29 males and 20 females) were identified as bicondylar TPF, the mean age 47.2 (27-69). All patients adopted the device and MIPO technique. A series of score, complications, and radiographs in the follow-up period, from three months, six months, one year, and two years and the last follow-up, were recorded, from visual analogue score (VAS), hospital for special surgery (HSS), and Short-Form 36 (SF-36), containing physical (PCS) and mental (MCS), and Rasmussen score. RESULTS: Forty-seven patients showed good functional recovery. No patients were lost, mean follow-up time was 28.17 ± 2.81 (24.2-35.4) months. Operation time was 89.80 ± 13.46 (58-110) min. At the last follow-up, VAS was 1.3 ± 0.92 (0-4), HHS was 93.10 ± 2.63 (89-99), PCS was 49.20 ± 7.40 (38-65), and MCS was 50.08 ± 4.77 (43-62). Complications were as follows: cutaneous necrosis (3, 6%), asymptomatic arthritis (3, 6%), symptomatic arthritis (1, 2%), and deep venous thrombosis (1, 2%). Mean fracture healing time was 11.82 ± 1.5 (10-15.4) weeks. All patients got recovery without extra surgery and removed the implants at 12.85 ± 0.76 (11.2-15.4) months. CONCLUSION: Temporary traction device of bilateral external fixator combined with MIPO technique was simple and convenient, with a smaller soft-tissue damage, an easier operational approach, and its worth being promoted.


Asunto(s)
Fracturas de la Tibia , Fracturas de la Meseta Tibial , Masculino , Femenino , Humanos , Persona de Mediana Edad , Fijadores Externos , Fijación Interna de Fracturas/métodos , Fijación de Fractura/métodos , Fracturas de la Tibia/cirugía , Hilos Ortopédicos , Tracción , Placas Óseas , Resultado del Tratamiento
2.
BMC Musculoskelet Disord ; 23(1): 1068, 2022 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-36471331

RESUMEN

BACKGROUND: The commonly used technique for treating unstable pelvic fractures with sacroiliac screws and anterior internal fixator (INFIX) is prone to complications, such as injury to the pelvic vasculature and nerves, life-threatening bleeding, lateral femoral cutaneous neuritis, and wound infection. This study investigated the clinical effects of using a modified percutaneous iliosacral screw and INFIX technique for treating unstable pelvic fractures. METHODS: A retrospective analysis of minimally invasive internal fixation using modified incision of an anterior-ring INFIX application combined with modified percutaneous iliosacral screw placement was performed for 22 cases of unstable pelvic fractures from January 2017 to December 2018. Based on the Tile classification, there were 4 type B1, 7 type B2, 5 type B3 and 6 type C1 injuries. Preoperatively, the length and orientation of the internal fixation were computer-simulated and measured. On postoperative day 3, pelvic radiographs and three-dimensional computed tomograms were used to assess fracture reduction and fixation. All patients were regularly followed up at 4 weeks, 12 weeks, 6 months, 12 months, 24 months and annually thereafter. Fracture healing, complications, visual analogue scale (VAS) scores, the quality of fracture repositioning and Majeed score were assessed during follow-up. RESULTS: All patients were followed up for a mean of 25.23 ± 1.48 months. All fractures healed without loss of reduction and no patient showed evidence of delayed union or nonunion. Two years postoperatively, the mean VAS score was 0.32 ± 0.09 and the mean Majeed score was 94.32 ± 1.86. CONCLUSION: The modified percutaneous iliosacral screw technique increases the anterior tilt of the sacroiliac screw by shifting the entry point posteriorly to increase the safety of the screw placement. Downward modification of the INFIX incision reduces the risk of lateral femoral cutaneous nerve injury. This technique is safe, effective and well tolerated by patients.


Asunto(s)
Fracturas Óseas , Huesos Pélvicos , Humanos , Estudios Retrospectivos , Huesos Pélvicos/diagnóstico por imagen , Huesos Pélvicos/cirugía , Huesos Pélvicos/lesiones , Fracturas Óseas/diagnóstico por imagen , Fracturas Óseas/cirugía , Tornillos Óseos , Fijación Interna de Fracturas/métodos , Fijadores Internos
3.
Phys Chem Chem Phys ; 23(18): 10964-10977, 2021 May 12.
Artículo en Inglés | MEDLINE | ID: mdl-33913464

RESUMEN

We present a computational study on nonadiabatic excited-state dynamics initiated from the 3p Rydberg states of trimethylamine (TMA). We utilise a methodology based on full-dimensional (39 D) trajectory surface-hopping (TSH) simulations, in which propagation is carried out on on-the-fly density functional theory (DFT)/time-dependent DFT (TD-DFT) potentials. Both our electronic structure benchmarks to high-level ab initio methods (EOM-CCSD, CASPT2) and TSH simulations demonstrate high-accuracy of the applied CAM-B3LYP functional for the description of Rydberg excited states. Based on our excited-state simulations, we construct the following mechanistic picture: when pumped resonantly to the 3p Rydberg manifold, TMA coherently vibrates along the planarisation mode with a period of 104 fs and an exponential coherence decay time constant of 240 fs. Nonadiabatic dynamics occur on a faster (∼1 ps) and a slower (∼3 ps) timescale, along the N-C stretching mode by mixing with a dissociative σN-C* state. As a minor relaxation channel, 3p → 3s internal conversion occurs via branching at the σN-C*/3s intersection. We find that photodissociaton is hardly observable within 3 ps (1%), which is a failure of the range-separated hybrid CAM-B3LYP functional, as a consequence of its static electron correlation deficiency at long range. In contrast, pure DFT (GGA-BLYP) provides an accurate long-range description (19% dissociation yield), also supported by comparison to recent ultrafast experiments, even if the Rydberg state energies are significantly underestimated (>1 eV). Finally, we reveal the crucial role of vibrational coherence and energy transfer from the planarisation mode for N-C bond activation and resulting nonadiabatic dynamics. The present work illustrates the importance of nuclear-electronic coupling for excited-state dynamics and branching at conical intersections.

4.
J Orthop Sci ; 26(3): 385-388, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-32229162

RESUMEN

BACKGROUND: This study assessed the reliability and validity of the modified Unified Classification System for femur fractures after hip arthroplasty. METHODS: Four hundred and two cases were evaluated by 6 observers, 3 experts and 3 trainee surgeons. Each observer read the radiographs on 2 separate occasions and classified each case as to its type. Reliability was assessed by looking at the intraobserver and interobserver agreement using the Kappa statistic. Validity was assessed within the B group by looking at the agreement between the radiographic classification and the intraoperative findings. Interobserver and intraobserver agreement and validity were analyzed, using weighted kappa statistics. RESULTS: The mean k value for interobserver agreement was found to be 0.882 (0.833-0.929) for consultants (almost perfect agreement) and 0.776 (0.706-0.836) for the trainees (substantial agreement). Intraobserver k values ranged from 0.701 to 0.972, showing substantial to almost perfect agreement. Validity analysis of 299 type B cases revealed 89.854% agreement with a mean k value of 0.849 (0.770-0.946) (almost perfect agreement). CONCLUSIONS: This study has shown that the modified Unified Classification System is reliable and valid. We believe it is useful to improve the judgment of the implant stability, and establish the therapeutic strategy for periprosthetic femoral fracture.


Asunto(s)
Artroplastia de Reemplazo de Cadera , Fracturas del Fémur , Fracturas Periprotésicas , Artroplastia de Reemplazo de Cadera/efectos adversos , Fracturas del Fémur/diagnóstico por imagen , Fracturas del Fémur/etiología , Fracturas del Fémur/cirugía , Fémur/cirugía , Humanos , Variaciones Dependientes del Observador , Fracturas Periprotésicas/diagnóstico por imagen , Fracturas Periprotésicas/etiología , Fracturas Periprotésicas/cirugía , Reproducibilidad de los Resultados
5.
J Foot Ankle Surg ; 60(5): 912-916, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33836970

RESUMEN

The present study was performed to evaluate the effects of the medial and anterolateral approach combined with internal fixation by double head compression screws and countersunk K-wires for Hawkins Ⅲ talus neck and medial malleolus fracture. Eleven patients with articular surface crush injury resulting in Hawkins Ⅲ talus neck fractures accompanied by medial malleolus fractures were reviewed. All patients underwent emergency operations. The fractures were fixed using double head compression screws and countersunk K-wires through combined medial and anterolateral approaches. FAOS, AOFAS ankle-hindfoot scale, and VAS questionnaire scores were recorded. In addition, ROM of the ankle and postoperative complications were assessed. All patients were followed up for a median of 52.45 ±â€…5.15 months. The multiple scales data of FAOS on the affected side were: pain score 89.14 ±â€…7.08; activities of daily living score 89.57 ±â€…8.88; quality-of-life score 89.20 ±â€…7.44; sports score 75.00 ±â€…15.49; and other symptoms score 84.74 ±â€…7.51. The mean overall AOFAS ankle-hindfoot score was 88.36 ±â€…6.39. The VAS score was 0.72 ±â€…0.65. Ankle motion included dorsiflexion (13.18°â€…±â€…9.02°) and plantar flexion (32.27°â€…±â€…12.34°). Subtalar joint motion included eversion (10.91°â€…±â€…7.01°) and inversion (11.36°â€…±â€…7.45°). All scores of the healthy side were higher than those of the affected side (p < .05). In addition to ROM of the ankle and subtalar joint and sports score, various indicators of recovery rate had scores > 80%. One patient developed skin necrosis, which healed after debridement and wound dressing. Late complications included subtalar and/or ankle traumatic arthritis in six patients, four of whom showed no obvious clinical symptoms. In conclusion, the method of emergency surgery and medial and anterolateral approach combined with countersunk K-wires to fix small bone fragments to restore the integrity of the articular surface is acceptable for Hawkins Ⅲ talus neck with medial malleolus fracture.


Asunto(s)
Fracturas de Tobillo , Lesiones por Aplastamiento , Astrágalo , Actividades Cotidianas , Fracturas de Tobillo/diagnóstico por imagen , Fracturas de Tobillo/cirugía , Fijación Interna de Fracturas , Humanos , Astrágalo/diagnóstico por imagen , Astrágalo/cirugía , Resultado del Tratamiento
6.
J Chem Phys ; 149(24): 244104, 2018 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-30599730

RESUMEN

We propose an "automatic" approach to analyze the results of the on-the-fly trajectory surface hopping simulation on the multi-channel nonadiabatic photoisomerization dynamics by considering the trajectory similarity and the configuration similarity. We choose a representative system phytochromobilin (P Φ B) chromophore model to illustrate the analysis protocol. After a large number of trajectories are obtained, it is possible to define the similarity of different trajectories by the Fréchet distance and to employ the trajectory clustering analysis to divide all trajectories into several clusters. Each cluster in principle represents a photoinduced isomerization reaction channel. This idea provides an effective approach to understand the branching ratio of the multi-channel photoisomerization dynamics. For each cluster, the dimensionality reduction is employed to understand the configuration similarity in the trajectory propagation, which provides the understanding of the major geometry evolution features in each reaction channel. The results show that this analysis protocol not only assigns all trajectories into different photoisomerization reaction channels but also extracts the major molecular motion without the requirement of the pre-known knowledge of the active photoisomerization site. As a side product of this analysis tool, it is also easy to find the so-called "typical" or "representative" trajectory for each reaction channel.


Asunto(s)
Biliverdina/análogos & derivados , Simulación de Dinámica Molecular , Algoritmos , Biliverdina/química , Biliverdina/efectos de la radiación , Análisis por Conglomerados , Isomerismo , Procesos Fotoquímicos
7.
Orthop Surg ; 16(1): 263-268, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37814793

RESUMEN

OBJECTIVE: Heel fractures need extensive surgical incisions and are challenging to successfully reposition using traditional prying. The goal of this study is to evaluate the clinical effectiveness of using a Kirschner pin-guided distractor to treat inversion shortening calcaneal fractures in the "out-in" position. METHODS: A total of 40 data from 37 patients with inversion shortened calcaneal fractures from January 2018 to March 2020 were reviewed. Preoperative lateral and axial X-rays and 3D CT were taken to assess the fracture type, and minimally invasive internal fixation was performed in the "out-in" position with distractor repositioning, and intraoperative and postoperative images were taken to assess fracture repositioning and fixation. During the follow-up period, the postoperative functional recovery status was assessed using the VAS score, AOFAS score, and FAOS score. Paired-samples t-test was used for all data comparisons. RESULTS: All cases received a mean follow-up of 28.49 ± 3.25 months, and the mean fracture healing time was 7.84 ± 0.71 weeks. The postoperative images showed well-fixed fracture repositioning, and calcaneal height, length, width, and inversion angles were significantly improved. At the final follow-up, the calcaneal height, length, and width recovered from 39.35 ± 4.44mm, 79.35 ± 2.7mm, and 45.75 ± 2.87mm preoperatively to 50.93 ± 3.18mm, 82.23 ± 1.90mm, and 39.67 ± 1.58mm postoperatively (p < 0.001; p < 0.001; p < 0.001). The calcaneus inversion angle restored from 7.73° ± 2.26° to 3.80° ± 1.80° (p < 0.001). Böhler's angle and Gissane's angle improved from 13.13° ± 3.02° and 105.15° ± 8.94° to 27.95° ± 3.41° and 122.85° ± 5.54° (p < 0.001; p < 0.001). No non-healing fractures, osteomyelitis, or traumatic arthritis were observed. CONCLUSION: Minimally invasive internal fixation with distractor repositioning in the "out-in" position is effective in the treatment of inversion shortening calcaneal fractures while restoring the anatomy and protecting the soft tissue.


Asunto(s)
Traumatismos del Tobillo , Calcáneo , Traumatismos de los Pies , Fracturas Óseas , Traumatismos de la Rodilla , Humanos , Estudios de Seguimiento , Fracturas Óseas/diagnóstico por imagen , Fracturas Óseas/cirugía , Fijación Interna de Fracturas/métodos , Resultado del Tratamiento , Calcáneo/cirugía , Traumatismos de los Pies/cirugía , Estudios Retrospectivos
8.
ACS Nano ; 18(10): 7485-7495, 2024 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-38415599

RESUMEN

Homovanillic acid (HVA) is a major dopamine metabolite, and blood HVA is considered as central nervous system (CNS) dopamine biomarker, which reflects the progression of dopamine-associated CNS diseases and the behavioral response to therapeutic drugs. However, facing blood various active substances interference, particularly structurally similar catecholamines and their metabolites, real-time and accurate monitoring of blood HVA remains a challenge. Herein, a highly selective implantable electrochemical fiber sensor based on a molecularly imprinted polymer is reported to accurately monitor HVA in vivo. The sensor exhibits high selectivity, with a response intensity to HVA 12.6 times greater than that of catecholamines and their metabolites, achieving 97.8% accuracy in vivo. The sensor injected into the rat caudal vein tracked the real-time changes of blood HVA, which paralleled the brain dopamine fluctuations and indicated the behavioral response to dopamine increase. This study provides a universal design strategy for improving the selectivity of implantable electrochemical sensors.


Asunto(s)
Catecolaminas , Dopamina , Ratas , Animales , Ácido Homovanílico/metabolismo , Encéfalo/metabolismo
9.
Adv Mater ; : e2409137, 2024 Oct 24.
Artículo en Inglés | MEDLINE | ID: mdl-39449216

RESUMEN

Gels are formed by fluids that expand throughout the whole volume of 3D polymer networks. To unlock unprecedented properties, exploring new fluids immobilized in polymer networks is crucial. Here, a new liquid metal-polymer gel material termed "metalgel" is introduced via fluid replacement strategy, featuring 92.40% vol liquid metal fluid as a continuum immobilized by interconnected nanoscale polymer network. The unique structure endows metalgel with high electrical conductivity (up to 3.18 × 106 S·m‒1), tissue-like softness (Young's modulus as low as 70 kPa), and low gas permeability (4.50 × 10‒22 m2·s‒1·Pa‒1). Besides, metalgel demonstrates electrical stability under extreme deformations, such as being run over by a 4.5-metric-tonne truck, and maintains its integrity in various environments for up to 180 days. The immobilization of high-volume-fraction liquid metal fluid is realized by electrostatic interactions is further revealed. Potential applications for metalgel are diverse and include soft electromagnetic shielding, hermetic sealing, and stimulating/sensing electrodes in implantable bioelectronics, underscoring its broad applicability.

10.
Indian J Orthop ; 57(4): 571-576, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37006729

RESUMEN

Objective: This study aimed to investigate the clinical efficacy of closed reduction high-strength sutures combined with Nice knots in treating transverse patella fractures. Method: We retrospectively analyzed the clinical data of 28 patients who underwent surgery for transverse patella fractures from January 2019 to January 2020. Twelve cases of the study group were treated with closed reduction high-strength sutures combined with Nice knots, and 16 cases in the control group were treated with tension band wiring. Observations included patellar healing, follow-up knee mobility with Böstman score, Lysholm score, surgical data, postoperative complications, and secondary surgery rate. Result: No statistically significant difference was observed between the two groups in the Patient demographic data, with a mean follow-up of 13.14 ± 1.58 months. There was no delayed healing or deep infection in the two groups. In the control group, 2 cases of internal fixation failure and 1 case of superficial infection were observed. The differences in mean fracture healing time, follow-up Böstman score, Lysholm score and knee mobility between the two groups were not statistically different. However, the differences were statistically significant for the duration of surgery, Incision length, intraoperative bleeding and the secondary surgery rate was lower in the study group. Conclusion: Closed reduction high-strength sutures have good clinical efficacy in treating transverse patella fractures, with the advantages of shorter duration of surgery and Incision length,less intraoperative bleeding and no secondary removal.

11.
Medicine (Baltimore) ; 102(25): e34098, 2023 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-37352071

RESUMEN

RATIONALE: Currently, there are no clear guidelines to determine whether and when to perform surgical hip repair in patients with acute stroke and hip fracture. PATIENT CONCERNS: In this case report, we report a case of 75-year-old woman admitted with left hip pain and limited mobility for 1 month. DIAGNOSES: Patient had a history of acute cerebral infarction 42 days ago, and diagnosed with a left intertrochanteric fracture at another hospital 30 days ago. INTERVENTION: Patient was treated with closed reduction and internal fixation with proximal femoral nail anti-rotation. OUTCOMES: At 2-year follow-up, the patient's basic function was restored. The fracture healed well, and the Harris hip score was 75. LESSONS: Without consistent guidelines, individualized treatment strategies including surgical methods and timing of surgery should be made to weigh the risks and benefits for patients with acute stroke and intertrochanteric fractures.


Asunto(s)
Fijación Intramedular de Fracturas , Fracturas de Cadera , Accidente Cerebrovascular , Femenino , Humanos , Anciano , Hemiplejía/complicaciones , Hemiplejía/cirugía , Estudios Retrospectivos , Resultado del Tratamiento , Clavos Ortopédicos , Fijación Interna de Fracturas , Fracturas de Cadera/complicaciones , Fracturas de Cadera/cirugía , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/cirugía
12.
Sci Rep ; 13(1): 14330, 2023 08 31.
Artículo en Inglés | MEDLINE | ID: mdl-37653006

RESUMEN

To investigate the clinical effects of specific Unified Classification System B (UCS B)-lesser trochanter periprosthetic fractures and determine whether they occur only with non-cemented stems. A retrospective analysis of 28 patients with specific UCS B2 fractures who underwent two surgical treatments, longer stem revision and internal fixation (LSRIF) and open reduction and internal fixation (ORIF), was performed. The patients were assessed at 1, 3, 6, 12, and 24 months and annually thereafter. Fracture healing, complications, Harris Hip Score (HHS), and the Short Form Health Survey questionnaire (SF-36) quality of life score were assessed at each follow-up. At the time of the last follow-up, seven patients had been lost: three were lost to contact, two died, and two were hospitalised elsewhere and unavailable for follow-up. The remaining 21 patients were followed for an average of 49.3 ± 15.4 (range: 24-74.4) months. Their average fracture healing time was 13.5 ± 1.1 (12-15.4) weeks. Complications included three cases (10.71%) of thrombus, one (3.57%) of heart failure, and one (3.57%) of pulmonary infection. There were no revisions due to prosthesis loosening, subsidence, or infection. At the last follow-up, the HHS, SF-36 mental score, and SF-36 physical score were recorded, LSRIF vs. ORIF (82.9 ± 6.6 vs. 74.7 ± 3.9, p = 0.059; 50.9 ± 7.6 vs. 38 ± 1.4, p = 0.012, and 51.7 ± 8.4 vs. 39.7 ± 3.4, p = 0.032, respectively). Specific UCS B2 fractures mostly occur with non-cemented stems. LSRIF with cables is the main treatment, while ORIF is an option for those elderly in poor condition.


Asunto(s)
Fracturas Periprotésicas , Anciano , Humanos , Fracturas Periprotésicas/etiología , Fracturas Periprotésicas/cirugía , Calidad de Vida , Estudios Retrospectivos , Fijación Interna de Fracturas/efectos adversos , Fémur
13.
Injury ; 50(2): 571-578, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30587333

RESUMEN

BACKGROUND: This study assessed the surgical outcomes of Lisfranc injuries accompanied by multiple metatarsal fractures. Metatarsal fractures here refers to metatarsal head, neck, and shaft (including shaft fractures accompanied by fractures of the base) fractures, as well as mixed (i.e., segmental fracture) fractures, as seen on imaging studies. METHODS: Between 2002 and 2015, one hundred and seventy-six patients were followed-up for a mean of 92 months, including eight patients who underwent secondary arthrodesis due to severe arthritis after ORIF. All the patients underwent surgical fusion (primary partial arthrodesis, PPA; n = 78) or non-fusion (percutaneous or open reduction and internal fixation, ORIF; n = 98) procedures and the outcomes were evaluated by clinical examinations, radiography, visual analogue scale (VAS) pain score, the American Orthopaedic Foot and Ankle Society (AOFAS) midfoot score, the Foot and Ankle Outcome Score (FAOS), and the Short Form (SF)-36 physical and SF-36 mental questionnaires. The parameters between the fusion and non-fusion groups were analyzed by repeated-measures ANOVA. Statistically significant differences between the two groups were then further analyzed using a two-independent-samples t-test. RESULTS: Anatomical reduction was achieved in 161 patients. At the last follow-up, the mean AOFAS score was 74.67 (range: 39-91) in the non-fusion group and 82.79 (range: 67-97) in the fusion group (P = 0.003). The PPA and ORIF groups differed significantly with respect to the VAS pain score (1.93 vs. 1.21), the SF-36 physical (75.87 vs. 80.90) and mental (75.76 vs. 81.33) components, and the FAOS pain (72.74 vs. 84.06), symptoms (71.87 vs. 82.49), activities of daily life (ADLs: 73.12 vs. 81.54), sport/recreation (sport/rec: 57.99 vs. 73.23), and quality of life (QoL: 79.95 vs. 86.67) components. In the ORIF group, 23 patients had mild/moderate post-traumatic osteoarthritis. CONCLUSIONS: With longer and more conservative postoperative management, fusion results in a better outcome than non-fusion in the treatment of Lisfranc injuries accompanied by multiple metatarsal fractures.


Asunto(s)
Traumatismos de los Pies/cirugía , Fijación Interna de Fracturas , Fracturas Óseas/cirugía , Luxaciones Articulares/cirugía , Huesos Metatarsianos/lesiones , Traumatismo Múltiple/cirugía , Reducción Abierta , Adulto , Femenino , Estudios de Seguimiento , Traumatismos de los Pies/fisiopatología , Fracturas Óseas/fisiopatología , Humanos , Luxaciones Articulares/fisiopatología , Masculino , Persona de Mediana Edad , Traumatismo Múltiple/fisiopatología , Radiografía , Estudios Retrospectivos , Resultado del Tratamiento , Adulto Joven
14.
J Phys Chem Lett ; 9(11): 2725-2732, 2018 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-29732893

RESUMEN

We discuss a theoretical approach that employs machine learning potential energy surfaces (ML-PESs) in the nonadiabatic dynamics simulation of polyatomic systems by taking 6-aminopyrimidine as a typical example. The Zhu-Nakamura theory is employed in the surface hopping dynamics, which does not require the calculation of the nonadiabatic coupling vectors. The kernel ridge regression is used in the construction of the adiabatic PESs. In the nonadiabatic dynamics simulation, we use ML-PESs for most geometries and switch back to the electronic structure calculations for a few geometries either near the S1/S0 conical intersections or in the out-of-confidence regions. The dynamics results based on ML-PESs are consistent with those based on CASSCF PESs. The ML-PESs are further used to achieve the highly efficient massive dynamics simulations with a large number of trajectories. This work displays the powerful role of ML methods in the nonadiabatic dynamics simulation of polyatomic systems.

15.
J Chem Theory Comput ; 13(10): 4611-4623, 2017 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-28862858

RESUMEN

On-the-fly trajectory-based nonadiabatic dynamics simulation has become an important approach to study ultrafast photochemical and photophysical processes in recent years. Because a large number of trajectories are generated from the dynamics simulation of polyatomic molecular systems with many degrees of freedom, the analysis of simulation results often suffers from the large amount of high-dimensional data. It is very challenging but meaningful to find dominating active coordinates from very complicated molecular motions. Dimensionality reduction techniques provide ideal tools to realize this purpose. We apply two dimensionality reduction approaches (classical multidimensional scaling and isometric feature mapping) to analyze the results of the on-the-fly surface-hopping nonadiabatic dynamics simulation. Two representative model systems, CH2NH2+ and the phytochromobilin chromophore model, are chosen to examine the performance of these dimensionality reduction approaches. The results show that these approaches are very promising, because they can extract the major molecular motion from complicated time-dependent molecular evolution without preknown knowledge.

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