The Role of Total Antioxidant Status in Cerebral Vasoreactivity of Chronic Obstructive Pulmonary Disease Patients

Introduction: Chronic obstructive pulmonary disease (COPD) is associated with an oxidant-antioxidant imbalance. COPD patients have impaired cerebral vasoreactivity (CVR). Impaired CVR could be correlated with total antioxidant status (TAS) in plasma. Aim: To determine the role of systemic TAS in CVR of COPD patients. Material and Methods: In this cross-sectional observational study, we included 120 participants (the mean age of 67±7.9, 87 males), 90 COPD patients categorized according to the severity of airway obstruction in mild, moderate, severe/very severe and 30 age- and sex-matched controls. We analyzed baseline mean flow velocities (MFV) of the middle cerebral artery (MCA) and the basilar artery (BA), the mean breath-holding index (BHIm) of those arteries (BHImMCA and BHImBA) by transcranial Doppler ultrasound and TAS in plasma. The level of significance was set to α=0.05. Results: A significant negative correlation between TAS and BHImBA (Rho=−0.445, P=0.01) was found only in the mild COPD group. In COPD groups, baseline MFV BA is in a significant positive correlation with BHImMCA and BHImBA (Rho=0.336, P=0.001 and Rho=0.647, P<0.001). According to the severity of airway obstruction in COPD groups, a significant positive correlation between baseline MFV BA and BHImBA was found: in mild (Rho=0.731, P<0.001), moderate (Rho=0.574, P=0.001) and severe/very severe (Rho=0.398, P=0.03). Conclusion: Systemic TAS was not correlated with CVR in all COPD groups. However, perfusion in the BA of COPD groups was in a significant positive correlation with the anterior and posterior CVR. The analysis of perfusion in the basal cerebral arteries should be part of a future study of CVR in COPD patients. (Hlavati M, Tomić S, Buljan K, Butković-Soldo S. The Role of Total Antioxidant Status in Cerebral Vasoreactivity of Chronic Obstructive Pulmonary Disease Patients. SEEMEDJ 2020; 4(2); 48-61

Croatian composers’ diseases – biopathographies

Presentation of the diseases among 25 significant croatian composers reveals some infectious diseases (tuberculosis, etc.) among the composers who had died young and some chronic non-infectious diseases (mostly malignant, inflammatory and cardiocerebral origin) among composers who died in old age. It is a part of the pathographic review of over 300 composers from the book »Diseases and destinies of famous composers«

Diseases and Destinies of Famous Composers Why should one even write about composers’ diseases?

Why should one even write about composers’ diseases? That question is no longer an issue because in the last 50 to 100 years, this very topic has given us a whole new insight into famous composers’ creative lives. Grieg, as well as many others, concurred. The very goal of biopathographies is to investigate the lives and creativity of famous composers from the psychological as well as from medical point of view. We attempted to list and interpret the data we found accurately, and categorize them using a simple everyday vocabulary in the book Diseases and Destinies of Famous Composers.

Recent trends in concentrated photovoltaics concentrators' architecture

The field of concentrated photovoltaics (CPV) has met some remarkable advances in recent years. The continuous increase in conversion efficiency of multijunction solar cells and new advancements in optics have led to new demands and opportunities for optical design in CPV. This paper is a mini-review on current requirements for CPV optical design, and it presents some of the main trends in recent years on CPV systems architecture

Design, manufacturing and measurements of a metal-less V-groove RXI collimator

A metal-less RXI collimator has been designed. Unlike to the conventional RXI collimators, whose back surface and central part of the front surface have to be metalized, this collimator does not include any mirrored surface. The back surface is designed as a grooved surface providing two TIR reflections for all rays impinging on it. The main advantage of the presented design is lower manufacturing cost since there is no need for the expensive process of metalization. Also, unlike to the conventional RXI collimators this design performs good colour mixing. The first prototype of V-groove RXI collimator has been made of PMMA by direct cutting using a five axis diamond turning machine. The experimental measurements of the first prototype are presented

Improving performances of fresnel cpv system: fresnel-rxi köhler concentrator

A novel and advanced photovoltaic concentrator optic is presented comprising a Fresnel lens and a dielectric solid RXI as a secondary optical element, both with free-form surfaces (i.e. neither rotational nor linear symmetry). The RXI secondary is designed with the Simultaneous Multiple Surface (SMS) design method of Nonimaging Optics. In the secondary optics rays undergo refraction (R), reflection (X) and total internal reflection (I), so SMS nomenclature [2] for the device is RXI assigning letters to each surface that deflects rays. This is the first time the RXI-type geometry has been applied to design a photovoltaic secondary element. The LPI patented Fresnel- RXI Köhler concentrator [1] produces both the desired light concentration with high tolerance (high acceptance angle) as well as high irradiance uniformity on the solar cell achieved by Köhler integration method. The optical performance of the FRXI device (F denotes a Fresnel lens surface) will be presented as well as comparison with other conventional Fresnel-based CPV concentrators and application of the designed syste

Towards 35% Efficient Concentrator Modules Based On LPI Köhler Concentrators With External Confinement Cavities

Multijunction solar cells present a certain reflectivity on its surface that lowers its light absorption. This reflectivity produces a loss in electrical efficiency and thus a loss in global energy production for CPV systems. We present here an optical design for recovering this portion of reflected light, and thus leading to a system efficiency increase. This new design is based on an external confinement cavity, an optical element able to redirect the light reflected by the cell towards its surface again. We have proven the excellent performance of these cavities integrated in CPV modules offering outstanding results: 33.2% module electrical efficiency @Tcell  =  25 °C and relative efficiency and Isc gains of over 6

High-efficiency Köhler photovoltaic concentrators with external light confinement

Metal grid lines are a vital element in multijunction solar cells in order to take out from the cell the generated photocurrent. Nevertheless all this implies certain shadowing factor and thus certain reflectivity on cells surface that lowers its light absorption. This reflectivity produces a loss in electrical efficiency and thus a loss in global energy production for CPV systems. We present here an optical design for recovering this portion of reflected light, and thus leading to a system efficiency increase. This new design is based on an external confinement cavity, an optical element able to redirect the light reflected by the cell towards its surface again. It has been possible thanks to the recent invention of the advanced Köhler concentrators by LPI, likely to integrate one of these cavities easily. We have proven the excellent performance of these cavities integrated in this kind of CPV modules offering outstanding results: 33.2% module electrical efficiency @Tcell=25ºC and relative efficiency and Isc gains of over 6%