Influence of the Electron Deficient Co‐Monomer on the Optoelectronic Properties and Photovoltaic Performance of Dithienogermole‐based Co‐Polymers

A series of donor–acceptor (D–A) conjugated polymers utilizing 4,4‐bis(2‐ethylhexyl)‐4H‐germolo[3,2‐b:4,5‐b′]dithiophene ( DTG ) as the electron rich unit and three electron withdrawing units of varying strength, namely 2‐octyl‐2H‐benzo[d][1,2,3]triazole ( BTz ), 5,6‐difluorobenzo[c][1,2,5]thiadiazole ( DFBT ) and [1,2,5]thiadiazolo[3,4‐c]pyridine ( PT ) are reported. It is demonstrated how the choice of the acceptor unit ( BTz , DFBT , PT ) influences the relative positions of the energy levels, the intramolecular transition energy (ICT), the optical band gap (E_g^opt), and the structural conformation of the DTG ‐based co‐polymers. Moreover, the photovoltaic performance of poly[(4,4‐bis(2‐ethylhexyl)‐4H‐germolo[3,2‐b:4,5‐b′]dithiophen‐2‐yl)‐([1,2,5]thiadiazolo[3,4‐c]pyridine)] ( PDTG‐PT ), poly[(4,4‐bis(2‐ethylhexyl)‐4H‐germolo[3,2‐b:4,5‐b′]dithiophen‐2‐yl)‐(2‐octyl‐2H‐benzo[d][1,2,3]triazole)] ( PDTG‐BTz ), and poly[(4,4‐bis(2‐ethylhexyl)‐4H‐germolo[3,2‐b:4,5‐b′]dithiophen‐2‐yl)‐(5,6‐difluorobenzo[c][1,2,5]thiadiazole)] ( PDTG‐DFBT ) is studied in blends with [6,6]‐phenyl‐C₇₀‐butyric acid methyl ester ( PC₇₀BM ). The highest power conversion efficiency (PCE) is obtained by PDTG‐PT (5.2%) in normal architecture. The PCE of PDTG‐PT is further improved to 6.6% when the device architecture is modified from normal to inverted. Therefore, PDTG‐PT is an ideal candidate for application in tandem solar cells configuration due to its high efficiency at very low band gaps (E_g^opt = 1.32 eV). Finally, the 6.6% PCE is the highest reported for all the co‐polymers containing bridged bithiophenes with 5‐member fused rings in the central core and possessing an E_g^opt below 1.4 eV.     

Land use and electricity generation: A life-cycle analysis

Renewable-energy sources often are regarded as dispersed and difficult to collect, thus requiring substantial land resources in comparison to conventional energy sources. In this review, we present the normalized land requirements during the life cycles of conventional- and renewable-energy options, covering coal, natural gas, nuclear, hydroelectric, photovoltaics, wind, and biomass. We compared the land transformation and occupation matrices within a life-cycle framework across those fuel cycles. Although the estimates vary with regional and technological conditions, the photovoltaic (PV) cycle requires the least amount of land among renewable-energy options, while the biomass cycle requires the largest amount. Moreover, we determined that, in most cases, ground-mount PV systems in areas of high insolation transform less land than the coal-fuel cycle coupled with surface mining. In terms of land occupation, the biomass-fuel cycle requires the greatest amount, followed by the nuclear-fuel cycle. Although not detailed in this review, conventional electricity-generation technologies also pose secondary effects on land use, including contamination and disruptions of the ecosystems of adjacent lands, and land disruptions by fuel-cycle-related accidents.     

Emissions from photovoltaic life cycles.

Photovoltaic (PV) technologies have shown remarkable progress recently in terms of annual production capacity and life cycle environmental performances, which necessitate timely updates of environmental indicators. Based on PV production data of 2004-2006, this study presents the life-cycle greenhouse gas emissions, criteria pollutant emissions, and heavy metal emissions from four types of major commercial PV systems: multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride. Life-cycle emissions were determined by employing average electricity mixtures in Europe and the United States during the materials and module production for each PV system. Among the current vintage of PV technologies, thin-film cadmium telluride (CdTe) PV emits the least amount of harmful air emissions as it requires the least amount of energy during the module production. However, the differences in the emissions between different PV technologies are very small in comparison to the emissions from conventional energy technologies that PV could displace. As a part of prospective analysis, the effect of PV breeder was investigated. Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies. At least 89% of air emissions associated with electricity generation could be prevented if electricity from photovoltaics displaces electricity from the grid.     

Magnetic flux emergence and associated dynamic phenomena in the Sun

We present a review of the process of magnetic flux emergence in the Sun. We focus on observations and numerical experiments that explore the dynamical rise of magnetic fields from the solar interior to the corona. We describe the response of the highly stratified solar atmosphere on flux emergence and, consequently, we present a comprehensive picture of the coupling between solar dynamic events and flux emergence. We discuss potential applications of this process in other astrophysical environments.     

Early Signs of Atherogenic Features in the HDL Lipidomes of Normolipidemic Patients Newly Diagnosed with Type 2 Diabetes

Cardiovascular disease (CVD) is the major cause of death in patients with type-2 diabetes mellitus (T2DM), although the factors that accelerate atherosclerosis in these patients are poorly understood. The identification of the altered quantity and quality of lipoproteins, closely related to atherogenesis, is limited in routine to a pattern of high triglycerides and low HDL-cholesterol (HDL-C) and in research as dysfunctional HDLs. We used the emerging NMR-based lipidomic technology to investigate compositional features of the HDLs of healthy individuals with normal coronary arteries, drug-naïve; recently diagnosed T2DM patients with normal coronary arteries; and patients with recent acute coronary syndrome. Patients with T2DM and normal serum lipid profiles even at diagnosis presented significant lipid alterations in HDL, characterized by higher triglycerides, lysophosphatidylcholine and saturated fatty acids; and lower cholesterol, phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, plasmalogens and polyunsaturated fatty acids, an atherogenic pattern that may be involved in the pathogenesis of atherosclerosis. These changes are qualitatively similar to those found, more profoundly, in normolipidemic patients with established Coronary Heart Disease (CHD). We also conclude that NMR-based lipidomics offer a novel holistic exploratory approach for identifying and quantifying lipid species in biological matrixes in physiological processes and disease states or in disease biomarker discovery.     

Flame synthesis of mixed tin‐silver‐copper nanopowders and conductive coatings

The single‐step direct synthesis of tin‐silver‐copper nanopowders and nanostructured coatings using the flame‐based high‐temperature reducing jet (HTRJ) process is reported. Nanostructured coatings were deposited and sintered within the HTRJ reactor to study the effect of reductive sintering temperature on their electrical conductivity and surface morphology. Although the ultimate application of these nanoparticles is in printed electronics, which requires dispersing them as stable inks before depositing and sintering them, our approach of direct deposition from the gas phase provides an upper limit on the conductivity achievable with a given composition. The directly deposited coatings had high electrical conductivity, including a value of 2 × 10⁶ S/m for 36 wt % Cu‐40 wt % Ag‐24 wt % Sn sintered at 200°C. This is twice the conductivity of a pure silver coating prepared under similar conditions. Moreover, similarly high electrical conductivity was achieved using only 20% Ag with sintering at 300°C. © 2015 American Institute of Chemical Engineers AIChE J, 62: 408–414, 2016     

A Numerical Model for Two-Dimensional Flood Routing in Complex Terrains

In this paper, a new powerful numerical hydrodynamic in-house model is presented and tested. The model simulates flood routing in two dimensions. It is based on the solution of Shallow Water Equations using the Finite Difference Method according to the explicit McCormack numerical scheme which has shock capturing capability. The innovation of the proposed model lies in the modification of McCormack scheme by incorporating artificial viscosity through a diffusion factor in order to avoid oscillations as proposed by various researchers. Additionally, a threshold of water depth is introduced in order to distinguish the wet and dry cells of the computational domain. The model is capable of producing maps for the inundation extent, water depths and depth-averaged water velocities. Finally, the paper presents extensive testing of the model by comparison with analytical solution, experimental results and with the output of another software package in real world flood simulation studies.     

Multiple-loop feedback filters using current feedback amplifiers

Novel high-order filter topologies realised by employing current feedback operational amplifiers as active elements are introduced in this article. These are constructed from multiple-loop feedback paths and could be utilised for the realisation of filters of arbitrary order and type. An offered benefit is the requirement for employing only grounded capacitors and resistors. Two design examples are provided and the correct operation of the corresponding topologies has been evaluated through experimental results.