Determination of charge transfer dynamics and efficiency in solar cells sensitized with carbazole, indoline and triphenylamine dyes

Wydział FizykiNiniejsza praca została poświęcona badaniom dynamiki procesów transferu ładunku zachodzących w ogniwach słonecznych sensybilizowanych barwnikiem (ang. Dye Sensitized Solar Cells – DSSC), zawierających wysoko wydajne barwniki karbazolowe, indolinowe i trifenylaminowe. W opublikowanych artykułach, wchodzących w skład cyklu stanowiącego przedmiot tej rozprawy, opisaliśmy, jak różnorodne modyfikacje, stosowane w celu poprawienia funkcjonowania ogniw, wpływają na ultraszybkie i szybkie procesy transferu ładunku oraz jak dynamika poszczególnych procesów związana jest z całościowym funkcjonowaniem ogniw. W celu uzyskania informacji o dynamice procesów transferu ładunku, ich wydajności oraz o powiązaniu tych cech z parametrami fotowoltaicznymi ogniw, wykorzystano szeroki zakres technik eksperymentalnych, obejmujący podstawową charakterystykę fotowoltaiczną i różnorodne metody stacjonarnej i czasowo rozdzielczej spektroskopii optycznej. Część wstępna (rozdziały 1 – 4) zawiera wprowadzenie opisujące stan wiedzy na temat układów DSSC. Praca zawiera również dokładne objaśnienie metodyki wytwarzania ogniw DSSC jak również opis najważniejszych technik wykorzystanych do ich badań. Publikacje naukowe, wchodzące w skład niniejszej pracy, podsumowane zostały w rozdziale piątym i zamieszczone za rozdziałem nr 6, gdzie podsumowano konkluzje pracy.The main concern of this thesis is the dynamics of charge transfer processes occurring in Dye Sensitized Solar Cells (DSSC) comprising a top efficient carbazole, indoline and triphenylamine dyes. This dissertation is based on a series of papers reporting the effects of different modifications applied to improve DSSCs on ultrafast and fast charge transfer processes and relation between the dynamics of particular charge transfer phenomena and the overall DSSC performance. In order to gain the information on the dynamics of charge transfer processes, their efficiency and relationship with the overall photovoltaic performance of studied devices, a broad range of experimental techniques was applied, including basic photovoltaic characterization methods, electrochemical impedance spectroscopy, and a variety of stationary and time resolved optical spectroscopy methods. The opening part of the dissertation (chapters 1 – 4) provides an introduction to the current state of knowledge on DSSC. Subsequently, main experimental methods including fabrication and key characterization techniques used for purposes of this thesis are thoroughly described. The scientific papers making the basis of this thesis are described in chapter 5 and attached after chapter 6 presenting the conclusions.I kindly acknowledge the financial support from the Polish National Science Centre under project 2015/18/E/ST4/00196

Equivalent circuits used in the diagnostics of insulation in power transformers

An equivalent circuit of the insulation system in power transformers comes in many forms. In tests for the dielectric loss tangent (tgδ) of the main insulation, the equivalent circuit has been simplified to two-terminal RC series connected or parallel connected circuits. For direct current tests of groundwall insulation modelling, two two-terminals circuits are required – one for charging and shorting, the other for the voltage recovering after shorting. The model turn-to-turn insulation may also be presented by two-terminal circuits. The parameters of the two-terminal circuit can be determined by direct current. The tested winding is energized by DC voltage, the current is interrupted and the voltage waveform on the terminals of the winding is recorded. The parameters of turn-to-turn insulation (equivalent circuit parameters) are calculated from the voltage waveform and they can be used for diagnostic purposes

WNT signaling regulates self-renewal and differentiation of prostate cancer cells with stem cell characteristics

Prostate cancer cells with stem cell characteristics were identified in human prostate cancer cell lines by their ability to form from single cells self-renewing prostaspheres in non-adherent cultures. Prostaspheres exhibited heterogeneous expression of proliferation, differentiation and stem cell-associated makers CD44, ABCG2 and CD133. Treatment with WNT inhibitors reduced both prostasphere size and self-renewal. In contrast, addition of Wnt3a caused increased prostasphere size and self-renewal, which was associated with a significant increase in nuclear Β-catenin, keratin 18, CD133 and CD44 expression. As a high proportion of LNCaP and C4-2B cancer cells express androgen receptor we determined the effect of the androgen receptor antagonist bicalutamide. Androgen receptor inhibition reduced prostasphere size and expression of PSA, but did not inhibit prostasphere formation. These effects are consistent with the androgen-independent self-renewal of cells with stem cell characteristics and the androgen-dependent proliferation of transit amplifying cells. As the canonical WNT signaling effector Β-catenin can also associate with the androgen receptor, we propose a model for tumour propagation involving a balance between WNT and androgen receptor activity. That would affect the self-renewal of a cancer cell with stem cell characteristics and drive transit amplifying cell proliferation and differentiation. In conclusion, we provide evidence that WNT activity regulates the self-renewal of prostate cancer cells with stem cell characteristics independently of androgen receptor activity. Inhibition of WNT signaling therefore has the potential to reduce the self-renewal of prostate cancer cells with stem cell characteristics and improve the therapeutic outcome.Peer reviewe

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Determination of charge transfer dynamics and efficiency in solar cells sensitized with carbazole, indoline and triphenylamine dyes

Wydział FizykiNiniejsza praca została poświęcona badaniom dynamiki procesów transferu ładunku zachodzących w ogniwach słonecznych sensybilizowanych barwnikiem (ang. Dye Sensitized Solar Cells – DSSC), zawierających wysoko wydajne barwniki karbazolowe, indolinowe i trifenylaminowe. W opublikowanych artykułach, wchodzących w skład cyklu stanowiącego przedmiot tej rozprawy, opisaliśmy, jak różnorodne modyfikacje, stosowane w celu poprawienia funkcjonowania ogniw, wpływają na ultraszybkie i szybkie procesy transferu ładunku oraz jak dynamika poszczególnych procesów związana jest z całościowym funkcjonowaniem ogniw. W celu uzyskania informacji o dynamice procesów transferu ładunku, ich wydajności oraz o powiązaniu tych cech z parametrami fotowoltaicznymi ogniw, wykorzystano szeroki zakres technik eksperymentalnych, obejmujący podstawową charakterystykę fotowoltaiczną i różnorodne metody stacjonarnej i czasowo rozdzielczej spektroskopii optycznej. Część wstępna (rozdziały 1 – 4) zawiera wprowadzenie opisujące stan wiedzy na temat układów DSSC. Praca zawiera również dokładne objaśnienie metodyki wytwarzania ogniw DSSC jak również opis najważniejszych technik wykorzystanych do ich badań. Publikacje naukowe, wchodzące w skład niniejszej pracy, podsumowane zostały w rozdziale piątym i zamieszczone za rozdziałem nr 6, gdzie podsumowano konkluzje pracy.The main concern of this thesis is the dynamics of charge transfer processes occurring in Dye Sensitized Solar Cells (DSSC) comprising a top efficient carbazole, indoline and triphenylamine dyes. This dissertation is based on a series of papers reporting the effects of different modifications applied to improve DSSCs on ultrafast and fast charge transfer processes and relation between the dynamics of particular charge transfer phenomena and the overall DSSC performance. In order to gain the information on the dynamics of charge transfer processes, their efficiency and relationship with the overall photovoltaic performance of studied devices, a broad range of experimental techniques was applied, including basic photovoltaic characterization methods, electrochemical impedance spectroscopy, and a variety of stationary and time resolved optical spectroscopy methods. The opening part of the dissertation (chapters 1 – 4) provides an introduction to the current state of knowledge on DSSC. Subsequently, main experimental methods including fabrication and key characterization techniques used for purposes of this thesis are thoroughly described. The scientific papers making the basis of this thesis are described in chapter 5 and attached after chapter 6 presenting the conclusions.I kindly acknowledge the financial support from the Polish National Science Centre under project 2015/18/E/ST4/00196