Determination of the refractive-index change in the excited state based on transient absorption microscopy.

Photoinduced excited-state carriers can affect both the absorption coefficient and refractive index of materials and influence the performance of photoelectric devices. Femtosecond time-resolved pump-probe transient absorption (TA) spectroscopy is usually used to detect carrier dynamics and excited-state absorption coefficients; however, measurements of transient refractive-index change are still difficult. We propose a method for determining the excited-state refractive-index change using TA microscopy. In TA measurements, a Fabry-Pérot cavity formed by the front and back surfaces of the sample could lead to interference of the probe light. As the wavelength of standing waves in the Fabry-Pérot cavity is closely related to the refractive index, the carrier-induced excited-state refractive-index change was obtained by comparing the transmission probe spectra between the ground and excited states. The proposed method was used to study the dynamics of excited-state refractive-index change in a perovskite film.

Exploration of Risk Factors for Pancreatic Cancer and Development of a Clinical High-Risk Group Rating Scale.

(1) Background: There are few studies on people at high risk for clinical pancreatic cancer (PC). We aimed to explore the risk factors of PC and establish a scale for identifying high-risk populations of clinical PC. (2) Methods: We conducted a matched case-control study, retrospectively collecting demographic data and common clinical indicators from all subjects. Logistic regression was used to explore the risk factors of PC. Based on these factors, we created a high-risk population rating scale, which showed a higher diagnostic value. (3) Results: 385 cases and 428 controls were finally enrolled in our study. Multivariate analysis showed that body mass index (BMI) below 18.5 kg/m2 (OR 5.944, 95%CI: 1.759~20.084), smoking (OR 2.745, 95%CI: 1.555~4.844), new-onset diabetes (OR 5.239, 95%CI: 2.091~13.125), low high-density lipoprotein cholesterol (HDL-C) levels (OR 1.790, 95%CI: 1.044~3.069), and carbohydrate antigen 19-9 (CA19-9) levels no less than 35 U/mL (OR 160.328, 95%CI: 83.392~308.243) were associated with an increased risk of PC, whereas high total cholesterol (TC) levels were related to a lower risk of PC (OR 0.392, 95%CI: 0.211~0.730). The high-risk population scale, whose area under the receiver operating curve reached 0.948 (p < 0.001), showed a greater clinical diagnostic value. (4) Conclusions: Smoking history, new-onset diabetes, BMI, TC, HDL-C, and CA19-9 levels were associated with the risk of PC. The high-risk population rating scale might be used for early clinical PC screening.