Open-Circuit Voltage in Inverted Polycarbazole:Fullerene Bulk Heterojunction Solar Cells

The correlation between cathode work function and open-circuit voltages (Voc) in inverted polycarbazole:fullerene (PCDTBT:PC70BM) bulk-heterojunction solar cells has been investigated by postannealing of indium tin oxide (ITO) electrodes. The ITO function is seen to change from 4.2 to 4.5 eV without the need to insert additional interfacial layers with annealing temperature up to 400 °C. The best device performance was obtained at room temperature with the ITO work function of 4.2 eV with a Voc of 0.89 eV, a Jsc of 8.06 mA·cm-2, a fill factor (FF) of 64.70%, and a power conversion efficiency of 4.62%. Together with previously published results, we are able to extract two regimes of Voc dependence on the cathode work function: first, a linear relationship when the cathode work function exceeds the lowest unoccupied molecular orbital (LUMO) of PCBM and, second, a constant Voc regime when the ITO work function reduces below the LUMO level. These results provide general guidelines for the cathode contact design in inverted polymer solar cells

A new approximation of Fermi-Dirac integrals of order 1/2 for degenerate semiconductor devices

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.spmi.2018.03.072 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/There had been tremendous growth in the field of Integrated circuits (ICs) in the past fifty years. Scaling laws mandated both lateral and vertical dimensions to be reduced and a steady increase in doping densities. Most of the modern semiconductor devices have invariably heavily doped regions where Fermi-Dirac Integrals are required. Several attempts have been devoted to developing analytical approximations for Fermi-Dirac Integrals since numerical computations of Fermi-Dirac Integrals are difficult to use in semiconductor devices, although there are several highly accurate tabulated functions available. Most of these analytical expressions are not sufficiently suitable to be employed in semiconductor device applications due to their poor accuracy, the requirement of complicated calculations, and difficulties in differentiating and integrating. A new approximation has been developed for the Fermi-Dirac integrals of the order 1/2 by using Prony's method and discussed in this paper. The approximation is accurate enough (Mean Absolute Error (MAE) = 0.38%) and easy enough to be used in semiconductor device equations. The new approximation of Fermi-Dirac Integrals is applied to a more generalized Einstein Relation which is an important relation in semiconductor devices

Liquid Metal Bandwidth-Reconfigurable Antenna

This letter shows how slugs of liquid metal can be used to connect/disconnect large areas of metalization and achieve a radiation performance not possible by using conventional switches. The proposed antenna can switch its operating bandwidth between ultrawideband and narrowband by connecting/disconnecting the ground plane for the feedline from that of the radiator. This could be achieved by using conventional semiconductor switches. However, such switches provide point-like contacts. Consequently, there are gaps in electrical contact between the switches. Surface currents, flowing around these gaps, lead to significant back radiation. In this letter, the slugs of a liquid metal are used to completely fill the gaps. This significantly reduces the back radiation, increases the bore-sight gain, and produces a pattern identical to that of a conventional microstrip patch antenna. Specifically, the realized gain and total efficiency are increased by 2 dBi and 24%, respectively. The antenna has potential applications in wireless systems employing cognitive radio (CR) and spectrum aggregation

Thermally stable solution processed vanadium oxide as a hole extraction layer in organic solar cells

Low-temperature solution-processable vanadium oxide (V2Ox) thin films have been employed as hole extraction layers (HELs) in polymer bulk heterojunction solar cells. V2Ox films were fabricated in air by spin-coating vanadium(V) oxytriisopropoxide (s-V2Ox) at room temperature without the need for further thermal annealing. The deposited vanadium(V) oxytriisopropoxide film undergoes hydrolysis in air, converting to V2Ox with optical and electronic properties comparable to vacuum-deposited V2O5. When s-V2Ox thin films were annealed in air at temperatures of 100 °C and 200 °C, OPV devices showed similar results with good thermal stability and better light transparency. Annealing at 300 °C and 400 °C resulted in a power conversion efficiency (PCE) of 5% with a decrement approximately 15% lower than that of unannealed films; this is due to the relative decrease in the shunt resistance (Rsh) and an increase in the series resistance (Rs) related to changes in the oxidation state of vanadium

Consumption of a flavonoid-rich acai meal is associated with acute improvements in vascular function and a reduction in total oxidative status in healthy overweight men

Background: Acai (Euterpe oleracea) is a polyphenol-rich fruit marketed as beneficial for health. Experimental data showing improvements in health markers arising from acai consumption in humans is limited. Objective: The objective of the present study was to investigate the effect of acai consumption on acute changes in vascular function and on other disease risk markers, including postprandial plasma insulin, glucose, and oxidative stress. Design: Twenty-three healthy male volunteers, aged 30–65 y and with a body mass index (in kg/m2) of 25–30, completed a randomized,controlled, high-fat challenge, double-blind, crossover, acute dietary intervention trial. The volunteers consumed either an acai-based smoothie (AS) or a macronutrient-matched control smoothie (PS) together with a high-fat breakfast meal challenge. The primary endpoint was the assessment of endothelial function in the brachial artery by flow-mediated dilatation (FMD). Results: The acute consumption of an AS containing 694 mg total phenolics improved vascular function, with postprandial increases in FMD from baseline of 1.4% at 2 h compared with 0.4% after consumption of the PS (P = 0.001) and increases at 6 h of 0.8% for the AS compared with 20.3% for the PS (P , 0.001). There was also a significantly lower incremental area under the curve (iAUC)for total peroxide oxidative status after acai consumption relative to the control. No significant changes were observed in blood pressure,heart rate, or postprandial glucose response. However, the first postprandial insulin peak (after breakfast) and the iAUC for insulin were elevated for the AS relative to the PS. Conclusions: In this acute study in overweight men, acai consumption was associated with improvements in vascular function, which may lower the risk of a cardiovascular event. Future intervention studies, perhaps with a chronic design, in wider populations and with other biomarkers of disease risk are needed to fully elucidate the benefits of acai to health

Head injury evaluation and ambulance diagnosis (HOME) study protocol: a feasibility study assessing the implementation of the Canadian CT Head Rule in the prehospital setting

Introduction Traumatic brain injury (TBI) is a common presentation in the prehospital environment. At present, paramedics do not routinely use tools to identify low-risk patients who could be left at scene or taken to a local hospital rather than a major trauma centre. The Canadian CT Head Rule (CCHR) was developed to guide the use of CT imaging in hospital. It has not been evaluated in the prehospital setting. We aim to address this gap by evaluating the feasibility and acceptability of implementing the CCHR to patients and paramedics, and the feasibility of conducting a full-scale clinical trial of its use. Methods and analysis We will recruit adult patients who are being transported to an emergency department (ED) by ambulance after suffering a mild TBI. Paramedics will prospectively collect data for the CCHR. All patients will be transported to the ED, where deferred consent will be taken and the treating clinician will reassess the CCHR, blinded to paramedic interpretation. The primary clinical outcome will be neurosurgically significant TBI. Feasibility outcomes include recruitment and attrition rates. We will assess acceptability of the CCHR to paramedics using the Ottawa Acceptability of Decision Rules Instrument. Interobserver reliability of the CCHR will be assessed between paramedics and the treating clinician in the ED. Participating paramedics and patients will be invited to participate in semistructured interviews to explore the acceptability of trial processes and facilitators and barriers to the use of the CCHR in practice. Data will be analysed thematically. We anticipate recruiting approximately 100 patients over 6 months. Ethics and dissemination This study was approved by the Health Research Authority and the Research Ethics Committee (REC reference: 22/NW/0358). The results will be published in a peer-reviewed journal, presented at conferences and will be incorporated into a doctoral thesis. Trial registration number ISRCTN92566288

Towards exploring current challenges and future opportunities relating to the prehospital triage of patients with traumatic brain injury: a mixed-methods study protocol

Introduction Traumatic brain injury (TBI) is a major global health burden that results in disability and loss of health. Identifying those patients who require specialist neuroscience care can be challenging due to the low accuracy of existing prehospital trauma triage tools. Despite the widespread use of decision aids to ‘rule out’ TBI in hospitals, they are not widely used in the prehospital environment. We aim to provide a snapshot of current prehospital practices in the UK, and to explore facilitators and challenges that may be encountered when adopting new tools for decision support. Methods and analysis A mixed-methods study will be conducted using a convergent design approach. In the first phase, we will conduct a national survey of current practice in which every participating ambulance service in the UK will receive an online questionnaire, and only one response is required. In the second phase, semistructured interviews will be conducted to explore the perceptions of ambulance service personnel regarding the implementation of new triage methods that may enhance triage decisions. The survey questions and the interview topic guide were piloted and externally reviewed. Quantitative data will be summarised using descriptive statistics; qualitative data will be analysed thematically. Ethics and dissemination This study has been approved by the Health Research Authority (REC reference 22/HRA/2035). Our findings may inform the design of future care pathways and research as well as identify challenges and opportunities for future development of prehospital triage tools for patients with suspected TBI. Our findings will be published in peer-reviewed journals, relevant national and international conferences, and will be included in a PhD thesis

Performance optimization of inorganic Cs2TiBr6 based perovskite solar cell via numerical simulation

Perovskite solar cells (PSCs) are considered highly efficient and hold great potential for next-generation photovoltaic devices due to their excellent properties. However, there are some challenges that hinder their mass production, such as toxicity in lead-based PSCs, nonstability, and high manufacturing costs. This study aims to address these challenges by proposing a device modeling approach to optimize the design of highly efficient lead-free cesium titanium bromide (Cs2TiBr6) perovskite solar cells. Cs2TiBr6-based perovskite solar cells have low performance due to the lack of suitable electron and hole transport layers. Therefore, this study utilizes numerical simulations in SCAPS-1D to investigate the effect of different parameters, including the doping density of optimized hole and electron transport layers, the thickness of the absorber layer, the NA/ND of the absorption layer, and the defect concentration. The study models six different device structures with different hole transport layerss. However, an optimized novel structure device Se/CuSbS2/Cs2TiBr6/IZGO/FTO/Glass has been proposed, with a theoretical power conversion efficiency of 29.19%. This device has a VOC of 1.33 V, JSC of 24.28 mA cm−2, and FF of 90.46%. Overall, this study demonstrates the potential of Cs2TiBr6 as a promising material for perovskite solar cells, providing a nontoxic, green renewable energy solution for the future

Glyceraldehyde-3-phosphate dehydrogenase subunits A and B are essential to maintain photosynthetic efficiency

In plants, glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12) reversibly converts 1,3-bisphosphoglycerate to glyceraldehyde-3-phosphate coupled with the reduction of NADPH to NADP+. The GAPDH enzyme that functions in the Calvin Benson Cycle is assembled either from four glyceraldehyde-3-phosphate dehydrogenase A subunits (GAPA) proteins forming a homotetramer (A4) or from two GAPA and two glyceraldehyde-3-phosphate dehydrogenase B subunit (GAPB) proteins forming a heterotetramer (A2B2). The relative importance of these two forms of GAPDH in determining the rate of photosynthesis is unknown. To address this question, we measured the photosynthetic rates of Arabidopsis (Arabidopsis thaliana) plants containing reduced amounts of the GAPDH A and B subunits individually and jointly, using T-DNA insertion lines of GAPA and GAPB and transgenic GAPA and GAPB plants with reduced levels of these proteins. Here we show that decreasing the levels of either the A or B subunits decreased the maximum efficiency of CO2 fixation, plant growth, and final biomass. Finally, these data showed that the reduction in GAPA protein to 9% wild-type levels resulted in a 73% decrease in carbon assimilation rates. In contrast, eliminating GAPB protein resulted in a 40% reduction in assimilation rates. This work demonstrates that the GAPA homotetramer can compensate for the loss of GAPB, whereas GAPB alone cannot compensate fully for the loss of the GAPA subunit