[Analysis of saliva cotinine and 3'-hydroxynicotinine concentration levels among restaurant workers in six cities of China]

This study was conducted between November to December 2020, consisting of six representative cities, Beijing, Shanghai, Shenzhen (with comprehensive smoke-free legislation), and Changsha, Chongqing, Shenyang (without comprehensive smoke-free legislation), 678 subjects were enrolled eventually, the mean age of the 678 subjects was (35.61±12.91)years old. Subjects from cities with comprehensive smoke-free legislation accounted for 49.71% of the total; male subjects accounted for 19.47%; meanwhile subjects from large, medium, and small restaurants accounted for 13.57% (92), 37.32% (253) and 49.11% (333) respectively. The analysis results indicate that the positive rate of restaurants staff of cotinine and 3'-hydroxynicotinine was lower in cities with comprehensive smoke-free legislation(34.12% vs 68.04%, χ²=78.01, P<0.001; 16.32% vs 41.94%, χ²=53.79, P<0.001), with staff from cities with comprehensive smoke-free legislation have lower concentrations of cotinine and 3'-hydroxynicotinine than their counterparts from cities without comprehensive smoke-free legislation(0.250 ng/ml vs 0.742 ng/ml, P<0.001; 0.250 ng/ml vs 0.250 ng/ml, P<0.001). No statistically significant difference in the concentration of cotinine and 3'-hydroxynicotinine in saliva between staff from restaurants of different sizes was detected (P>0.05).

Prognostic significance of preoperative radiotherapy in stage II and III rectal cancer patients: A Strobe-compliant study of SEER 18 registries database (1988-2011)

Preoperative radiation therapy has been regarded as the optional neoadjuvant treatment to decrease local recurrence of rectal cancer in addition to surgery. However, its benefit in survival remained obscure. This study was aimed to measure the efficacy of preoperative radiation therapy for survival in stage II and III rectal cancer patients. Retrospective cohort study used the database of Surveillance, Epidemiology and End Results program of the National Cancer Institute in the United States from 1988 to 2011. A total of 49439 patients diagnosed with primary rectal cancer who underwent surgery were included. Clinicopathological characteristics and rectal cancer-specific survival between surgery alone group and surgery plus preoperative radiation therapy group were compared. Rectal cancer patients in surgery plus preoperative radiation therapy group had significantly better survival than those in surgery alone group (72.70% vs. 66.61%, P < 0.001), as well as stratified by stages (stage II: 77.4% vs. 74.3%, P < 0.001; stage III: 68.3% vs. 58.6%, P < 0.001). However, this beneficial impact was only observed after 2000s (P < 0.001). Multivariate survival analysis revealed that preoperative radiation therapy was an independent predictor for better survival in stage III (hazard ratio, 0.795; 95% CI, 0.753-0.840; P < 0.001), but not in stage II (P = 0.70). Preoperative radiation therapy might bring a better survival in stage II and III rectal cancer patients, but only as an independent predictor for stage III patients. As time progressed, preoperative radiation therapy might yield more profit for stage II and III rectal cancer patients.

Efficient optical coupling in AlGaN/GaN quantum well infrared photodetector via quasi-one-dimensional gold grating

In this letter, a new kind of grating, quasi-one-dimensional gold grating, has been proposed to enhance the optical coupling in AlGaN/GaN quantum well infrared photodetector (QWIP). The electric field distribution, current density and energy flow are analyzed by an algorithm of finite element method (FEM). Significantly enhanced electric field component E(z) perpendicular to multiple quantum wells (MQWs) is explained by introducing the resonant coupling of surface plasmon polariton (SPP) and localized surface plasmon (LSP). The |E(z)|(2) in MQWs reaches 0.85 (V/m(2) when the electric field intensity (|E(0)|(2)) of normal incidence is 1 (V/m(2) at 4.65 μm, showing 2 times and 1.3 times increase compared with that obtained via a one-dimensional gold grating and a two-dimensional gold grating, respectively. The results confirm that the quasi-one-dimensional gold grating provides more plasma excitation source and higher charge density with structure optimization, resulting in a high optical coupling efficiency of 85% in quantum well region.

Double-resonance enhanced intersubband second-order nonlinear optical susceptibilities in GaN/AlGaN step quantum wells

Second-order nonlinear optical susceptibilities for second harmonic generation (SHG) associated with intersubband transitions in GaN/AlGaN single quantum well and step quantum well have been studied theoretically by solving Schrödinger and Poisson equations self-consistently. The calculated results suggest that due to the very large polarization-induced field in the quantum well, the potential profile becomes asymmetrical, leading to large second-order susceptibilities. A high value about 4 × 10^-7 m/V can be obtained in single quantum well structure. Furthermore, by adopting step quantum well structure to increase the asymmetry degree of the potential profile and manipulate the energy levels for double-resonance, a significant enhancement of second-order susceptibility can occur in step quantum well. Specifically, the susceptibility can be as large as 4 × 10^-6 m/V with structure optimization, about an order of magnitude greater than that in single quantum well. The results indicate that nonlinear optical elements based on GaN/AlGaN step quantum wells are very promising for SHG in a wide range of wavelengths from telecommunication to mid-infrared, especially effective in longer wavelength.