Polarization-diverse absorption enhancement in thin-film organic photovoltaic devices using long-pitch plasmonic gratings

Organic photovoltaic (OPV) devices, which convert solar energy into electricity using organic semi-conductive polymers or small molecules, have shown great promise in renewable and green energy applications. Despite their flexibility, lightweight and low-cost, OPVs suffer from low power conversion efficiency (PCE). Recent progresses in the synthesis of new polymers and tandem solar cells promoted the PCE to 10.6%, as reported in Feb 2012, which is a great leap from the 2.5% reported in Feb 2001. In thin film solar cells including OPVs, however, the light absorption is intrinsically limited by the thinness of the photoactive layer, especially at wavelengths near the edge of their absorption band. Surface plasmon polaritons (SPPs), a hybrid of electron density oscillations and optical waves at dielectric/metal interfaces, have great potential in overcoming the limit in light absorption for three reasons. (1) SPPs are highly evanescent. When generated at the photoactive layer/metal electrode interface, SPPs benefit the optical absorption in thin-film solar cells by concentrating optical waves and their electromagnetic energy near the photoactive layer. (2) SPPs propagate along the supporting interface, which can be utilized to change the light path. As the light propagates sideways along the photoactive layer, the light path and thus the absorption are effectively increased. (3) SPPs have unique and tunable dispersion relations, i.e. their propagating speed and effective index can be controlled. This can be useful in engineering and combining the SPPs with other photonic phenomena for the absorption enhancement. In this thesis, I proposed to use silver (Ag) gratings to enhance the light absorption in P3HT:PCBM-based OPVs. To implement the Ag gratings in OPVs, I designed an substrate type inverted OPV architecture with light impinging on the device directly from the air side, in contrast to the traditional superstrate type OPVs with light impinging on the transparent substrate first and then the device. I showed, through finite element method (FEM) simulations, that with proper design of the grating geometry, we can achieve light absorption enhancement for linearly polarized light with all polarization angles, despite the fact that the Ag gratings are periodic only in one direction. The generation of propagating SPPs and the waveguide modes in the photoactive layer, are revealed as the two absorption enhancement mechanisms. Ag gratings are fabricated with electron beam lithography (EBL) combined with a lift-off process. The gratings and the OPVs with grating substrates were characterized with a micro-spectrometer, which showed more than 200% enhanced absorption at ~ 690 nm with the optimized grating design. The impacts of the grating pitch size, duty cycle and the height on the absorption enhancement were also studied with numerical analysis and experimental confirmation. In addition, this thesis also discusses the OPV device performance and the future prospective of plasmonics-assisted thin film solar cells

Bariatric Surgery Leads to a Reduction in Antibodies to Apolipoprotein A-1: a Prospective Cohort Study

Purpose: Autoantibodies against apolipoprotein A-1 have been associated with cardiovascular disease, poorer CV outcomes and all-cause mortality in obese individuals. The impact of bariatric surgery (BS) on the presence of circulating anti-apoA-1 IgG antibodies is unknown. This study aimed to determine the effect of bariatric surgery on auto-antibodies titres against Apolipoprotein A-1 (anti-apoA-1 IgG), looking for changes associated with lipid parameters, insulin resistance, inflammatory profile and percentage of excess body mass index loss (%EBMIL).Materials and methods: We assessed 55 patients (40 women) before, 6 and 12 months post-operatively. Baseline and post-operative clinical history and measurements of body mass index (BMI), serum cholesterol, triglycerides, high- and low-density lipoprotein cholesterol (HDL-C and LDL-C), apoA-1, highly sensitive C-reactive protein (hsCRP), fasting glucose (FG), glycated haemoglobin (HbA1c) and HOMA-IR were taken at each point. Human anti-apoA-1 IgG were measured by ELISA.Results: The mean age of participants was 50 years. BS significantly improved BMI, %EBMIL triglycerides, HDL-C, apoA-1, hsCRP, HBA1c, FG and HOMA-IR. Baseline anti-apoA-1 IgG seropositivity was 25% and was associated with lower apoA-1 and higher hsCRP levels. One year after BS, anti-apoA-1 IgG seropositivity decreased to 15% (p = 0.007) and median anti-apoA-1 IgG values decreased from 0.70 (0.56-0.84) to 0.47 (0.37-0.61) AU (p Conclusion: Bariatric surgery results in significant reduction in anti-apoA-1 IgG levels, which may adversely influence weight loss. The exact mechanisms underpinning these results are elusive and require further study before defining any clinical recommendations.</p

Polarization-diverse absorption enhancement in thin-film organic photovoltaic devices using long-pitch plasmonic gratings

Organic photovoltaic (OPV) devices, which convert solar energy into electricity using organic semi-conductive polymers or small molecules, have shown great promise in renewable and green energy applications. Despite their flexibility, lightweight and low-cost, OPVs suffer from low power conversion efficiency (PCE). Recent progresses in the synthesis of new polymers and tandem solar cells promoted the PCE to 10.6%, as reported in Feb 2012, which is a great leap from the 2.5% reported in Feb 2001. In thin film solar cells including OPVs, however, the light absorption is intrinsically limited by the thinness of the photoactive layer, especially at wavelengths near the edge of their absorption band. Surface plasmon polaritons (SPPs), a hybrid of electron density oscillations and optical waves at dielectric/metal interfaces, have great potential in overcoming the limit in light absorption for three reasons. (1) SPPs are highly evanescent. When generated at the photoactive layer/metal electrode interface, SPPs benefit the optical absorption in thin-film solar cells by concentrating optical waves and their electromagnetic energy near the photoactive layer. (2) SPPs propagate along the supporting interface, which can be utilized to change the light path. As the light propagates sideways along the photoactive layer, the light path and thus the absorption are effectively increased. (3) SPPs have unique and tunable dispersion relations, i.e. their propagating speed and effective index can be controlled. This can be useful in engineering and combining the SPPs with other photonic phenomena for the absorption enhancement. In this thesis, I proposed to use silver (Ag) gratings to enhance the light absorption in P3HT:PCBM-based OPVs. To implement the Ag gratings in OPVs, I designed an substrate type inverted OPV architecture with light impinging on the device directly from the air side, in contrast to the traditional superstrate type OPVs with light impinging on the transparent substrate first and then the device. I showed, through finite element method (FEM) simulations, that with proper design of the grating geometry, we can achieve light absorption enhancement for linearly polarized light with all polarization angles, despite the fact that the Ag gratings are periodic only in one direction. The generation of propagating SPPs and the waveguide modes in the photoactive layer, are revealed as the two absorption enhancement mechanisms. Ag gratings are fabricated with electron beam lithography (EBL) combined with a lift-off process. The gratings and the OPVs with grating substrates were characterized with a micro-spectrometer, which showed more than 200% enhanced absorption at ~ 690 nm with the optimized grating design. The impacts of the grating pitch size, duty cycle and the height on the absorption enhancement were also studied with numerical analysis and experimental confirmation. In addition, this thesis also discusses the OPV device performance and the future prospective of plasmonics-assisted thin film solar cells.</p

The Impact of Minimally Invasive Surgery on Treating Patients with Early Cervical Adenocarcinoma

Objective To explore the impact of minimally invasive surgery on treating patients with early cervical adenocarcinoma (CA). Methods From April 2016 to December 2019, patients with early CA and underwent surgery were prospectively included in this study. They were randomly divided into 2 groups: the minimally invasive surgery (MIS) group and conventional laparotomy (CL) group. The baseline characteristics, pathological features, surgical related parameters, serum tumor markers, complications and prognosis were analyzed and compared between the 2 groups. The risk factors for disease free survival (DFS) and overall survival (OS) were also analyzed with logistic regression analyses. Result The baseline characteristic and pathological features had no statistical difference between the 2 groups. The mean operation duration in MIS group was significantly longer than CL group (262.39 ± 34.98 vs 241.29 ± 36.98 min, P < 0.001). The intraoperative blood loss volume (189.87 ± 23.87 vs 306.87 ± 24.98 mL, P < 0.001), postoperative anal exhaust time (45.98 ± 4.39 vs 59.87 ± 4.87 days, P < 0.001), catheter removal time (18.29 ± 3.21 vs 21.53 ± 3.19 days, P < 0.001) and length of hospital stay (12.98 ± 2.09 vs 16.98 ± 2.32 days, P < 0.001) were significant lower in MIS group. The serum tumor markers decreased significantly postoperative in both groups with no different levels between the 2 groups. The incidence of complications had no difference between the 2 groups except lymphocysts (P = 0.023). After mean follow up time for 4.23 ± 0.34 years, the DFS rate and OS rate also had no statistical difference between the 2 groups (P = 0.069 and 0.151, respectively). Conclusion Extensive hysterectomy with MIS was equally efficacy and safe to CL

The role of N-glycosylation of CD200-CD200R1 interaction in classical microglial activation

Abstract Background Microglial inflammatory activation is the common feature of the central nervous system (CNS) diseases. Microglia can be activated and particularly polarized toward a dual role in the injured CNS. The CD200 receptor 1 (CD200R1) inhibits inflammatory microglia activation as illustrated by studies. Publications show abnormal activation of microglia secondary to the deficient inhibit of CD200-CD200R interaction. In the present study, we established a neuronal-microglia co-culture system to investigate the association between CD200R1 engagement and classical microglial activation. We analyzed the glycosylation of CD200R1 and the CD200 binding. Secretion of pro-inflammatory cytokines were measured. Results CD200R1 was N-glycosylated at Asparagine 44 (Asn44, N44). Mutation of this site disrupted CD200-CD200R1 interaction and up-regulated the expression of cytokines iNOS, CD86, IL-1β and TNF-α. Conclusion N44 of CD200R1 is a significant binding site for CD200-CD200R1 interaction and play a critical role in the maintenance of microglia. The N-glycosylation of CD200R1 could serve as a therapeutic agent for CNS inflammation