"On-the-Fly" Nonadiabatic Dynamics Simulation on the Ultrafast Photoisomerization of a Molecular Photoswitch Iminothioindoxyl: An RMS-CASPT2 Investigation.

Iminothioindoxyl (ITI) is a new class of photoswitch that exhibits many excellent properties including well-separated absorption bands in the visible region for both conformers, ultrafast Z to E photoisomerization as well as the millisecond reisomerization at room temperature for the E isomer, and switchable ability in both solids and various solvents. However, the underlying ultrafast photoisomerization mechanism at the atomic level remains unclear. In this work, we have employed a combination of high-level RMS-CASPT2-based static electronic structure calculations and nonadiabatic dynamics simulations to investigate the ultrafast photoisomerization dynamics of ITI. Based on the minimum-energy structures, minimum-energy conical intersections, linear interpolation internal coordinate paths, and nonadiabatic dynamics simulations, the overall photoisomerization scenario of ITI upon excitation is established. Upon excitation around 416 nm, the molecule will be excited to the S2 state considering its close energy to the experimentally measured absorption maximum and larger oscillator strength, from which ultrafast decay of S2 to S1 state can take place efficiently with a time constant of 62 fs. However, the photoisomerization is not likely to complete in the S2 state since the dihedral associated with the Z to E isomerization changes little during the relaxation. Upon relaxing to the S1 state, the molecule will decay to the S0 state ultrafast with a time constant of 232 fs. In contrast, the decay of the S1 state is important for the isomerization considering that the dihedral related to the isomerization of the hopping structures is close to 90°. Therefore, the S1/S0 intersection region should be important for the isomerization of ITI. Arriving at the S0 state, the molecule can either go back to the original Z reactant or isomerize to the E products. At the end of the 500 fs simulation time, the E configuration accounts for nearly 37% of the final structures. Moreover, the photoisomerization mechanism is different from the isomerization mechanism in the ground state; i.e., instead of the inversion mechanism in the ground state, the photoisomerization prefers the rotation mechanism. Our results not only agree well with previous experimental studies but also provide some novel insights that could be helpful for future improvements in the performance of the ITI photoswitches.

Prognosis analysis and risk factors related to progressive intracranial haemorrhage in patients with acute traumatic brain injury.

BACKGROUND: Since progressive intracranial haemorrhage (PIH) was introduced in neurosurgical literatures, several studies have been performed. PIH has been shown to be associated with a high increase in the risk of clinical worsening and related to morbidity and mortality as well. So, early detection and prediction of PIH is practically important in a clinical situation. OBJECTIVES: To investigate the risk factors related to PIH in patients with acute traumatic brain injury (TBI) and analyse their clinical significances. METHODS: PIH was confirmed by comparing the first and repeated CT scans. Data compared included gender, age, mechanism of injury, Glasgow Coma Score (GCS) at admission, timing from injury to the first CT, the signs of the initial CT scan, prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fg), thrombin time (TT), platelet (PLT) and D-dimer (D-D) values. Logistic regression analysis was used to show the risk factors related to PIH. RESULTS: A cohort of 498 patients with TBI was evaluated, and there were 139 (27.91%) patients who suffered from PIH. The differences between PIHs and non-PIHs were significant in age, GCS at admission, the signs of the initial CT scan (fracture, subarachnoid haemorrhage, brain contusion and primary haematoma), PT, Fg and D-D values (p < 0.001). Logistic regression analysis was used to identify that CT scans (subarachnoid haemorrhage, brain contusion and primary haematoma) and plasma D-D values as the most important predictors of PIH (p < 0.001). CONCLUSIONS: For patients with the initial CT scan showing subarachnoid haemorrhage, brain contusion and primary haematoma with abnormal D-D levels, an earlier and dynamic CT scan should be performed, for the detection of PIH as early as possible and the medical intervention would be enforced in time.

Early CT signs of progressive hemorrhagic injury following acute traumatic brain injury.

INTRODUCTION: Since progressive hemorrhagic injury (PHI) was introduced in neurosurgical literatures, several studies have been performed, the results of which have influenced doctors but do not define guidelines for the best treatment of PHI. PHI may be confirmed by a serial computerized tomography (CT) scan, and it has been shown to be associated with a fivefold increase in the risk of clinical worsening and is a significant cause of morbidity and mortality as well. So, early detection of PHI is practically important in a clinical situation. METHODS: To analyze the early CT signs of progressive hemorrhagic injury following acute traumatic brain injury (TBI) and explore their clinical significances, PHI was confirmed by comparing the first and repeated CT scans. Data were analyzed and compared including times from injury to the first CT and signs of the early CT scan. Logistic regression analysis was used to show the risk factors related to PHI. RESULTS: A cohort of 630 TBI patients was evaluated, and there were 189 (30%) patients who suffered from PHI. For patients with their first CT scan obtained as early as 2 h post-injury, there were 116 (77.25%) cases who suffered from PHI. The differences between PHIs and non-PHIs were significant in the initial CT scans showing fracture, subarachnoid hemorrhage (SAH), brain contusion, epidural hematoma (EDH), subdural hematoma (SDH), and multiple hematoma as well as the times from injury to the first CT scan (P < 0.01). Logistic regression analysis showed that early CT scans (EDH, SDH, SAH, fracture, and brain contusion) were predictors of PHI (P < 0.01). CONCLUSION: For patients with the first CT scan obtained as early as 2 h post-injury, a follow-up CT scan should be performed promptly. If the initial CT scan shows SAH, brain contusion, and primary hematoma with brain swelling, an earlier and dynamic CT scan should be performed for detection of PHI as early as possible and the medical intervention would be enforced in time.