bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Wavelength of Light on Solar Electrical Performance
Authors: Ibrahim Nagwa Ibrahim , Baher Edin Omer Manahil Mohammed
Published: October 2020

The photovoltaic effect takes place at the junction of two semiconducting materials. The relation between energy (E) of light (photons) and wavelength (lambda) is given the energy of the incident photons is inversely proportional to their wavelengths. Violet is the Short-wavelength radiation, occupy the end of the electromagnetic spectrum which includes ultraviolet radiation and gamma rays. On the other hand, long-wavelength radiation occupies the red end and includes infrared radiation, microwaves, and radio waves. The wavelengths of visible light occur between 400 and 700 nm, so the bandwidth wavelength for silicon solar cells is in the very near-infrared range. Any radiation with a longer wavelength, such as microwaves and radio waves, lacks the energy to produce, electricity from a solar cell. The cost-efficiency of photovoltaic solar panels maybe reducing by reflection losses is a major field of study in the solar glass market. The color from glass cover is an important factor for the performance of photovoltaic panels as it can turn out to be an active component in the design of PV panels. Indeed, different glass covers perform very differently under direct and diffuse radiance. Several factors poignant the parameters of the solar cells, wherever these factors influence the performance on the solar cells. An experiment was carried out to investigate current interdependence on each color’s wavelength, and to give the effect regarding color cover, what part of the light of spectrum would produce a maximum power out, and also the effect of changing the wavelength (color) on short circuit current, and open voltage circuit. The results show the smallest value of maximum power in the violet zone and the biggest value of maximum power in the red zone.
Dynamic Modeling and Simulation of a Solar Air Heater Assisted by a Dehumidification System for an Agriculture Greenhouse
Authors: Almehmadi Fahad , Hallinan Kevin
Published: October 2020

Appropriate greenhouse microclimate control is essential for optimizing plant growth and food production. But, maintenance of a greenhouse microclimate generally requires an excessive amount of energy. According to a report published by Scott Sanford [1], the energy cost for greenhouses is considered the third highest annual cost, behind labor and plant materials. At northern latitudes, heating is the primary energy requirement needed in an agriculture greenhouse, comprising 70 to 80% of a typical greenhouse energy consumption [1]. A reduction of heating energy is necessary to ensure the economic viability of a greenhouse.

This research investigates the potential energy savings associated with integrating a solar air heater assisted with a desiccant wheel in an agriculture greenhouse. This study has two main thrusts. The first is to demonstrate the energy effectiveness a solar air heater with a dehumidification system to maintain the internal climate. The second thrust is to develop a multi-linear regression model that can be used to predict the hourly heating requirement. Thereafter, the developed regression model can be used to conduct a parametric analysis to investigate the impact of changing greenhouse parameters on the total heating requirements.

A case study has been considered for a greenhouse that is 30 m long and 24 m wide. The climate condition of the city of Dayton, OH was selected for this case. The predicted performance of the integrated system is compared with two other heating systems: electric and gas furnaces. The study reveals that heating energy savings in the proposed system is 51% and 30% when compared with the electric and gas furnaces, respectively. Aside from heating energy savings, the proposed system can be efficiently used to control indoor humidity in a way that ensures better crop yield.
A Life Cycle Assessment of Biodiesel Fuel Produced From Waste Cooking Oil
Authors: Torres Hannah , Camacho Kayla , Macken Nelson
Published: October 2020

Biofuels have received considerable attention as a more sustainable solution for transportation fuels. Used vegetable oil, normally considered a waste product, has been suggested as a possible candidate. Herein we perform a life cycle assessment to determine the environmental impact of biodiesel fuel produced from waste vegetable oil. We present a cradle to fuel model that includes the following unit processes: growing and harvesting, soy oil processing, cooking, waste vegetable oil refining, transesterification to produce biodiesel fuel and transportation when required. For growing and harvesting, national historical data for yields, energy required for machinery, fertilizers (nitrogen, phosphorous and potassium), herbicides, pesticides and nitrous oxide production are considered. In soy oil processing, crushing and extraction using hexane are included. For cooking, typical fryer performance and food production are considered. In order to determine a mass balance for the cooking operation, oil carryout and waste oil removal are estimated. During waste oil refining, oil is filtered and water removed. Methanol and a catalyst are used in the process of transesterification with glycerin as a byproduct. Transportation is considered using diesel trucks. Data from GREET is used throughout to compute global warming potential (GWP) and energy consumption in terms of cumulative energy demand (CED). Mass allocation is applied to the soy meal produced in refining, oil utilized for cooking and glycerin produced during transesterification. Results are compared to traditional diesel fuel and gasoline. Individual processes are examined to determine possibilities for reduction of GWP and CED. Suggestions are made for improvements in environmental impact using alternative or more efficient methods. The study should provide useful information on the sustainability of biodiesel fuel produced from waste cooking oil.
Phase Change Thermal Diode Using Al2O3-Cu/Water Hybrid Nanofluids for Thermal Rectification Enhancement
Authors: Wong M. Y. , Tso C. Y. , Ho T. C.
Published: October 2020

A thermal diode, a device to manipulate the heat flow in different directions, is useful in various thermal systems, such as solar thermal storage systems. It is noted that the performance of phase change thermal diodes shows the highest thermal rectification performances in the literature. The performances of the phase change thermal diode can be further improved by utilizing a working fluid with enhanced thermal properties. Since hybrid nanofluids are proven to have better thermal properties than the base fluid (i.e. water), in this study, a thermal diode using Al2O3-Cu/water hybrid nanofluid is fabricated and tested to investigate the feasibility of using hybrid nanofluid to enhance the performance of the thermal diode. The heat transfer and thermal rectification performances of the thermal diode using Al2O3-Cu/water hybrid nanofluid are compared experimentally, to a thermal diode using water. The effect of temperature on the heat transfer and thermal rectification performances of the thermal diode is also examined. The results indicate that the effective thermal conductivity in the forward direction and the diodicity of the thermal diode using Al2O3-Cu/water hybrid nanofluid are improved by 42.4% and 30.8%, respectively, compared to that of the thermal diode using water. The findings not only reveal a new direction for future research in enhancement of the thermal rectification performance of the phase change thermal diode but also provide an alternative research path for improving the performance of existing solar thermal storage systems.
Novel Chemical Heatpump Technology for Thermoelectric Powerplants Cooling Needs
Authors: Zhou Gong , Shaaban Aly
Published: October 2020

With an increasing need to find ways to reduce water consumption in industrial cooling system, dry cooling has been of a great interest. To eliminate the dependence of powerplant cooling needs on water, a novel technology, called ACTIVE, has been developed. ACTIVE, is a novel chemical heatpump cycle, cools below the ambient wet bulb temperature with coefficient of performance (COP) reaching up to 30, outperforming current dry cooling technology especially during hot summer days. ACTIVE employs a cyclic depolymerization-polymerization process, based on readily available polymers and catalysts. In this effort the ACTIVE cycle was developed starting with a concept and was reduced to practice. Here the cycle is explained and test results are presented.
Wind Turbine Blade Coating Fatigue Induced by Raindrop Impact
Authors: Hu Weifei , Chen Weiyi , Wang Xiaobo , Liu Zhenyu , Tan Jianrong , Wang Yeqing
Published: October 2020

With the increase of wind energy production demand, the need to manufacture larger wind turbine blades is on the rise. Because of the high tip speed of the large blade, the blade could be impacted by high-speed objects such as raindrops. This research focuses on developing a computational model for analyzing wind turbine blade coating fatigue induced by raindrop impact. A stochastic rain texture model is used to simulate a realistic rain event determined by a rain intensity and a rain duration. A smoothed particle hydrodynamic approach is implemented to calculate the impact stress considering a single raindrop. A stress interpolation method is proposed to accurately and efficiently estimate the impact of stress under a random rain event. Besides, a crack growth law is used to explain the process of coating shedding. Through a method for calculating crack growth length based on stress, this paper analyzes crack growth life as a function of the rain intensity and the rain duration. This function, together with the statistics of rainfall history, provides a new approach for estimating the expected fatigue life of the blade coating.
Prediction of Wind Speed, Potential Wind Power, and the Associated Uncertainties for Offshore Wind Farm Using Deep Learning
Authors: Choe Do-Eun , Talor Gary , Kim Changkyu
Published: October 2020

Floating offshore wind turbines hold great potential for future solutions to the growing demand for renewable energy production. Thereafter, the prediction of the offshore wind power generation became critical in locating and designing wind farms and turbines. The purpose of this research is to improve the prediction of the offshore wind power generation by the prediction of local wind speed using a Deep Learning technique. In this paper, the future local wind speed is predicted based on the historical weather data collected from National Oceanic and Atmospheric Administration. Then, the prediction of the wind power generation is performed using the traditional methods using the future wind speed data predicted using Deep Learning. The network layers are designed using both Long Short-Term Memory (LSTM) and Bi-directional LSTM (BLSTM), known to be effective on capturing long-term time-dependency. The selected networks are fine-tuned, trained using a part of the weather data, and tested using the other part of the data. To evaluate the performance of the networks, a parameter study has been performed to find the relationships among: length of the training data, prediction accuracy, and length of the future prediction that is reliable given desired prediction accuracy and the training size.
Modeling and Control of Subcritical Coal-Fired Power Plant Components for Fault Detection
Authors: Agbleze Selorme , Lima Fernando V. , Indrawan Natarianto , Panday Rupendranath , Pezzini Paolo , Bonilla-Alvarado Harry , Bryden Kenneth M. , Tucker David , Shadle Lawrence J.
Published: October 2020

Due to the increased penetration of renewable power sources into the electric grid, the current number of existing coal-fired power plants shifting from baseload to load-following operations has also increased. This shift creates challenges especially for the power industry as coal-fired power plants were not designed for ramping situations, leading to added stress on major components of these plants. This stress causes the system to degrade over time and eventually develop faults. As boilers are still the primary component that fails and causes forced outages, accurate characterization of faults and fractures of boilers is now becoming increasingly critical to reduce plant downtime and extend the plant life during cycling operations. This work focuses on modeling sections of a subcritical coal-fired power plant and proposes algorithms for fault detection in MATLAB/Simulink. The developed model simulates the process dynamics including steam and feedwater flow regulating valves, drum-boiler, and heat rate on the regulation of pressure, drum level and production of saturated steam. The model also simulates the dynamics of superheaters for increasing the energy content of steam, and a spray section for regulating the temperature of steam upstream of the high-pressure turbine to allow for power output adjustment within a given valve operating range.

Furthermore, an extension to a leak detection framework proposed by co-authors in previous work is explored. The new framework includes a modification to the threshold analysis portion of the previous work. The extended framework is then applied to a subcritical coal-fired power plant model for leak detection. In particular, this framework analyzes mismatches or deviations in expected plant dynamics with an identified transfer function model. The mismatch is flagged after it exceeds a threshold. The developed algorithm thus aids in rapid detection of faults to reduce impeded plant performance. The results of this work will support real plant operations by providing an accurate characterization of faults in the operation of coal-fired power plants.
Theoretical Analysis of Solar Thermal Desalination Performance Limitation
Authors: Zheng Yanjie , Hatzell Kelsey B. , Caceres Gonzalez Rodrigo , Hatzell Marta C.
Published: October 2020

Solar thermal desalination systems utilize concentrated or non-concentrated sunlight to produce heat to drive a phase change separation process and produce freshwater. It could be an effective solution for increasingly scarce freshwater resources and energy shortages across the globe. In order to explore the performance limits and operating parameters that affect specific water production (SWP), this paper proposes a thermodynamic model of the ideal solar-driven thermal desalination process. The model compares two different heating configurations of solar collector system and considers surface temperature of solar collector, concentration ratio, recovery ratio and inlet saline water salinity to find maximum specific water production. The results show that under reversible condition, a flat plate collector with inlet saline water salinity of 35 g/kg will experience an increase in SWP from 29.9 gs−1m−2 to 52.7 gs−1m−2 if the recovery ratio decrease from 70% to 10%. For a system with concentration ratio of 10, when the surface temperature of solar collector is 507K, the maximum specific water production can reach 166.3 gs−1m−2 as the recovery ratio approaches zero. Reduction in incoming fluid salinity can further increase these performance limitations. The work fundamentally demonstrates the thermodynamic process of solar thermal desalination, and proposes a method to evaluate the performance limitation.
Using Machine Learning to Increase Model Performance for a Gas Turbine System
Authors: Hipple Samuel M. , Reinhart Zachary T. , Bonilla-Alvarado Harry , Pezzini Paolo , Bryden Kenneth Mark
Published: October 2020

With increasing regulation and the push for clean energy, the operation of power plants is becoming increasingly complex. This complexity combined with the need to optimize performance at base load and off-design condition means that predicting power plant performance with computational modeling is more important than ever. However, traditional modeling approaches such as physics-based models do not capture the true performance of power plant critical components. The complexity of factors such as coupling, noise, and off-design operating conditions makes the performance prediction of critical components such as turbomachinery difficult to model. In a complex system, such as a gas turbine power plant, this creates significant disparities between models and actual system performance that limits the detection of abnormal operations.

This study compares machine learning tools to predict gas turbine performance over traditional physics-based models. A long short-term memory (LSTM) model, a form of a recurrent neural network, was trained using operational datasets from a 100 kW recuperated gas turbine power system designed for hybrid configuration. The LSTM turbine model was trained to predict shaft speed, outlet pressure, and outlet temperature. The performance of both the machine learning model and a physics-based model were compared against experimental data of the gas turbine system. Results show that the machine learning model has significant advantages in prediction accuracy and precision compared to a traditional physics-based model when fed facility data as an input. This advantage of predicting performance by machine learning models can be used to detect abnormal operations.
Design of Fast and Reliable Steam Surface Condensers
Authors: Nadig Ranga
Published: October 2020

Power plants operating in cyclic mode, standby mode or as back up to solar and wind generating assets are required to come on line on short notice. Simple cycle power plants employing gas turbines are being designed to come on line within 10–15 minutes. Combined cycle plants with heat recovery steam generators and steam turbines take longer to come on line.

The components of a combined cycle plant, such as the HRSG, steam turbine, steam surface condenser, cooling tower, circulating water pumps and condensate pumps, are being designed to operate in unison and come on line expeditiously. Major components, such as the HRSG, steam turbine and associated steam piping, dictate how fast the combined cycle plant can come on line. The temperature ramp rates are the prime drivers that govern the startup time. Steam surface condenser and associated auxiliaries impact the startup time to a lesser extent.

This paper discusses the design features that could be included in the steam surface condenser and associated auxiliaries to permit quick startup and reliable operation. Additional design features that could be implemented to withstand the demanding needs of cyclic operation are highlighted.
Comparison Study of Two Different Integrated Solar Combined Cycle Systems
Authors: Duan Liqiang , Wang Zhen , Liu Yulei , Pang Liping
Published: October 2020

The thermodynamic performances of the two different integrated solar combined cycle (ISCC) systems are compared in this paper. Different from the previous comparison researches of ISCC systems based on different solar energy collecting technologies, the goal of this paper is to compare the integration characteristics of two different configurations of integrating concentrated solar energy into a gas turbine combined cycle (GTCC) system based on the same solar collector system. For the first kind of integrated solar gas-steam combined cycle system (ISCC1), the solar energy is introduced to the topping cycle of the gas-steam combined cycle system, while for the second kind of integrated solar gas-steam combined cycle system (ISCC2), the solar energy is introduced to the bottoming cycle of the GTCC system. The detailed system models are developed and their thermal performances are compared under different conditions. For ISCC1, the solar-to-electricity efficiency is higher than that of ISCC2 at the design condition when both the direct normal irradiation and ambient temperature are high due to more efficient energy conversion to electricity. However, the ISCC2 offers the advantages of higher solar-to-electricity efficiency and more solar power output when both the direct normal irradiation and ambient temperature are low. Two ISCC systems are good for energy saving, the ISCC1 consumes 4.412 × 108 kg of fuel a year, which is 2.803 × 106 kg less than that of ISCC2, and the ISCC1 has an annual solar-to-electricity efficiency of 23.93%, 0.88% higher than that of ISCC2. Detailed daily and monthly simulation results show that two systems have advantages of saving energy, and the simulations results show the obvious effects of different solar energy integration modes on the overall IGCC system performance. The achievements of this paper can offer valuable references for the design and operation optimization of ISCC system.
Effect of Magnetic Field on the Laminar Heat Transfer Performance of Hybrid Nanofluid in a Lid Driven Cavity Over Solid Block
Authors: Nimmagadda Rajesh , Matta Durga Prakash , Reuven Rony , Asirvatham Lazarus Godson , Wongwises Somchai , Yerramilli Anjaneyulu , Adusumilli Srinath
Published: October 2020

A 2D numerical investigation has been carried out to obtain the heat transfer performance of hybrid (Al2O3 + Ag) nanofluid in a lid driven cavity over solid block under the influence of uniform as well as non-uniform magnetic field. The geometrical domain consists of a cavity containing nanofluid that is driven by means of lid moving in one direction. This circulating nanofluid will extract enormous amount of heat from the solid block underneath the cavity resulting in conjugate heat transfer. A homogenous solver based on the finite volume method with conjugate heat transfer was developed and adopted in the existing study. The heat efficient hybrid nanofluid (HyNF) pair (2.4 vol.% Ag + 0.6 vol.% Al2O3) obtained by Nimmagadda and Venkatasubbaiah [1] is used in the present investigation. Moreover, efficient non-uniform sinusoidal magnetic field identified by Nimmagadda et al. [2] is also implemented and compared with uniform magnetic field. Furthermore, the magnetic field is applied over the geometrical domain along the two axial directions separately and the effective heat transfer performance is obtained. The significant impact of extensive parameters like Reynolds number, nanoparticle type, nanoparticle concentration, magnetic field type, magnetic field location and the strength of the magnetic field on heat transfer performance are systematically analyzed and presented.
Latent Dynamics in Siting Onshore Wind Energy Farms: A Case of a Wind Farm in South Africa
Authors: Adedeji Paul A. , Akinlabi Stephen , Madushele Nkosinathi , Olatunji Obafemi O.
Published: October 2020

Siting a renewable energy facility entails several latent but influential quantitative and qualitative variables. Empirical and analytical models often fail to unravel the dynamics of these variables however; prior knowledge of their existence and dynamics offers knowledge-based decision-making during the plant siting process. This article examines the significance and dynamics of land ownership, avian environment, and renewable energy policies. Asides the literature survey, review of government policy, and regulations, a semi-structured interview-based method was used in this study using a wind power plant in the Eastern Cape Province of South Africa as a case study. A qualitative content analysis was used for response analysis. From our findings, dynamics around land ownership could be complex depending on the land category and existing contracts between a landowner and the developer. Also, an in-extensive study of avian habitat in seemingly viable land could lead to forced-downtime of wind turbine generators at periods where production is notably high. Lastly, careful examination of prevailing renewable energy policies and a projection on future policies culminates into the viability of the investment. Trivializing these variables before site development could lead to investment loss through low-productivity or force-majeure in the investment. On the overall, the proposed solutions to these barriers can be useful for wind developers in solving similar problems in other renewable energy resources both in South Africa and other countries.
Study on Effects of Compressor Inlet Air Cooling on GTCC System Performance Under Different Environmental Conditions
Authors: Liqiang Duan , Yaofei Guo , Pan Pan , Yongxia Li
Published: October 2020

The environmental conditions (air temperature and relative humidity) have a great impact on the power and efficiency of gas turbine combined cycle (GTCC) system. Using the intake air cooling technology can greatly improve the performance of GTCC system. On the base of the PG9351FA gas turbine combined cycle system, this article builds the models of both the GTCC system and a typical lithium bromide absorption refrigeration system using Aspen Plus software. The effects of compressor inlet air cooling with different environmental conditions on the GTCC system performance are studied. The research results show that using the inlet air cooling technology can obviously increase the output powers of both the gas turbine and the combined cycle power. When the ambient humidity is low, the efficiency of GTCC changes gently; while the ambient humidity is high, the GTCC system efficiency will decline substantially when water in the air is condensed and removed with the progress of cooling process. At the same ambient temperature, when the relative humidity of the environment is equal to 20%, the gas turbine output power is increased by 35.64 MW, with an increase of 16.32%, and the combined cycle output power is increased by 39.57 MW, with an increase of 11.34%. At an ambient temperature of 35°C, for every 2.5 °C drop in the compressor inlet air, the thermal efficiency of the gas turbine increases by 0.189% compared to before cooling.
Modeling and Analysis of a Thermal Management System With Thermoelectric Cooling for the Application in Li-Ion Batteries
Authors: Mostafavi Amirhossein , Jain Ankur
Published: October 2020

Lithium-ion (Li-ion) batteries have recently become the main source of power in portable devices due to advantages such as high energy density. However, Li-ion cells operate well only in a specific temperature range. Degraded preperformance is a consequence of low temperature operation, and potential fire risk originates from thermal runaway at elevated temperatures. Efficient thermal management of Li-ion cells and battery packs is essential to ensure safe and durable performance in wide temperature range. Thermoelectric coolers (TECs), which have been used widely for electronics cooling may also be appropriate for battery cooling due to size compactness, working with direct current. This paper presents experimental characterization of cooling of a prismatic test cell with TECs on two sides. Cooling effect of TEC on the cell core and surface temperatures is investigated at different TEC power rates. Results show core and surface temperatures of the test cell decrease significantly. The obtained results show that by applying the TEC, a temperature drop of 10 °C was achieved for 0.75A TEC current. The optimum TEC current can be selected based on the application. In addition, numerical simulations are carried out to compare with experimental measurements. Heating effect of mounted TECs can be easily achieved just by changing current direction. Experimental results reveal TECs can heat up a cell in cold climate shortly. In addition, thermo electric module may also offer insulating effect in cold climate. Results presented in this paper illustrate potential application of thermoelectric cooling for thermal management of Li-ion cells.
Application of GE Low Load Package on an Existing District Heating Power Plant: A Case Study
Authors: Mambro Antonio , Congiu Francesco , Piraccini Francesco
Published: October 2020

The continuous increase of variable renewable energy and fuel cost requires steam turbine power plants to operate with high flexibility. Furthermore, the reduction in electricity price is forcing many existing and new district heating power plants to further optimize the heat production to maintain a sustainable business. This situation leads to low pressure steam turbines running at very low volume flow for an extended time.

In this work, a case study of an existing 30 MWel district heating power plant located in Europe is presented. The customer request was the removal of the steam turbine last two stages along with the condenser to maximize steam delivery for district heating operations. However, based on the experience gained by GE on low load during the last years, the same heat production has been guaranteed without any significant impact on the existing unit, excluding any major modification of the plant layout such as last stage blading and condenser removal. Making use of the latest low flow modeling, the minimum cooling flow through the low-pressure turbine has been reduced by more than 90% compared to the existing unit. Optimization of the hood spray system and logic will reduce trailing edge erosion during low load operation leading to a significant extension in the last stage blade lifetime. These modifications, commercialized by GE as the Advanced Low Load Package (ALLP), provide a cheap, flexible and effective solution for the customer.

With today’s knowledge, GE has the capability to guarantee low load operation minimizing the mass flow through the low-pressure turbine to the minimum required for safe operation. As a benefit to the customer, this option allows a gain in operational income of about 1.5 M€ per year.
Energy and Exergy Analysis of a Multi-Stage Hybrid Concentrated Solar Power Plant
Authors: Moreno-Gamboa Faustino , Nieto-Londoño César , Escudero-Atehortua Ana , Lopera Leonardo
Published: October 2020

The Colombian electricity sector is mainly composed of hydropower plants covering up to 70% of the total power generation. Several alternatives had been evaluated to complement Colombian’s energy mix, including solar PV and wind energy plants; however, there is no consensus about the appropriate solution in terms of the available resource, energy demand, and energy mix complementing. This work presents the performance evaluation of a hybrid thermosolar power plant at a city on the Caribbean Colombian coast, considering local environmental conditions such as ambient temperature and solar resource availability to attain the factor that constrain its optimal operating conditions. The overall energy and exergy plant efficiency is analyzed, considering an arbitrary number of stages. For instance, comparing a single-stage plant running with air with a two compression stages with inter-cooling and two expansion stages with reheating, the results indicate a 30 % higher exergy efficiency, and overall energy efficiency about 32 % larger and a fuel conversion rate around 18 % larger.
Finite-element numerical simulations of seismic attenuation in finely layered rocks
Authors: Picotti Stefano , Carcione José M. , Santos Juan E. , Gei Davide , Cavallini Fabio
Published: October 2020

P-wave conversion to slow diffusion (Biot) modes at mesoscopic (small-scale) inhomogeneities in porous media is believed to be the most important attenuation mechanisms at seismic frequencies. This study considers three periodic thin layers saturated with gas, oil, and water, respectively, a realistic scenario in hydrocarbon reservoirs, and perform finite-element numerical simulations to obtain the wave velocities and quality factors along the direction perpendicular to layering. The results are validated by comparison to the Norris-Cavallini analytical solution, constituting a cross-check for both theory and numerical simulations. The approach is not restricted to partial saturation but also applies to relevant properties in reservoir geophysics, such as porosity and permeability heterogeneities. This paper considers two cases, namely, the same rock skeleton and different fluids, and the same fluid and different dry-rock properties. Unlike the two-layer case (two fluids), the results show two relaxation peaks and the agreement between numerical and analytical solutions is excellent.
A healthy dose of fear
Authors: Ferrarelli Leslie K.
Published: October 2020

Secretion of IL-17a from meninges-resident T cells promotes anxiety-like behavior in mice.
Immunopathogenesis of Coronavirus-Induced Acute Respiratory Distress Syndrome (ARDS): Potential Infection-Associated Hemophagocytic Lymphohistiocytosis
Authors: Quan Chao , Li Caiyan , Ma Han , Li Yisha , Zhang Huali
Published: October 2020

The outbreak of coronavirus disease 2019 (COVID-19) in December 2019 in Wuhan, China, introduced the third highly pathogenic coronavirus into humans in the 21st century. Scientific advance after the severe acute respiratory syndrome coronavirus (SARS-CoV) epidemic and Middle East respiratory syndrome coronavirus (MERS-CoV) emergence enabled clinicians to understand the epidemiology and pathophysiology of SARS-CoV-2. In this review, we summarize and discuss the epidemiology, clinical features, and virology of and host immune responses to SARS-CoV, MERS-CoV, and SARS-CoV-2 and the pathogenesis of coronavirus-induced acute respiratory distress syndrome (ARDS).
Mechanisms of Drug-Induced Tolerance in Mycobacterium tuberculosis
Authors: Goossens Sander N. , Sampson Samantha L. , Van Rie Annelies
Published: October 2020

Successful treatment of tuberculosis (TB) can be hampered by
Mycobacterium tuberculosis
populations that are temporarily able to survive antibiotic pressure in the absence of drug resistance-conferring mutations, a phenomenon termed drug tolerance. We summarize findings on
M. tuberculosis
tolerance published in the past 20 years. Key
M. tuberculosis
responses to drug pressure are reduced growth rates, metabolic shifting, and the promotion of efflux pump activity.
Uncovering the high burden of hypertension and its predictors among adult population in Hosanna town, southern Ethiopia: a community-based cross-sectional study
Authors: Dereje Nebiyu , Earsido Alemu , Temam Layla , Abebe Ashenafi
Published: October 2020

Objective

Hypertension is a global public health problem, with its burden increasing particularly in developing countries. However, it has not yet received due attention in Ethiopia. The aim of this study was to determine the prevalence and associated factors of hypertension among adult population in Hosanna town, southern Ethiopia.

Design

Community-based cross-sectional study.

Setting

Hosanna town, southern Ethiopia.

Participants

Adult population aged ≥18 years (n=634) were recruited by a multistage stratified sampling technique.

Outcome measures

A face-to-face interview using structured questionnaire was carried out by trained nurses. Anthropometry and blood pressure were measured following standard procedures. Hypertension status was defined as systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg in two separate measurements or reported use of prescribed antihypertensive drugs for raised blood pressure. Factors associated with hypertension were identified by multivariable binary logistic regression analysis.

Results

The overall prevalence of hypertension was found to be 17.2% (19.3% and 14.2% among men and women, respectively). About 40% were unaware that they were hypertensive prior to the study. Older age ≥35 years (adjusted OR=3.9, 95% CI: 1.4 to 10.8), alcohol use (adjusted OR=3.4, 95% CI: 1.4 to 8.3), consumption of saturated oil (adjusted OR=6.5, 95% CI: 1.5 to 17.5) and unspecified different types of oil (adjusted OR=8.2, 95% CI: 1.9 to 25.1) and overweight/obesity (adjusted OR=2.9, 95% CI: 1.9 to 4.6) were found to be independently associated with hypertension.

Conclusions

The prevalence of both diagnosed and undiagnosed hypertension is alarmingly high in the town. These findings underscore the need to design health information provision systems on the risk factors of hypertension and promote good health practices. Blood pressure screening programmes at community levels to identify and treat undiagnosed hypertension should be considered.
Effect of clindamycin and a live biotherapeutic on the reproductive outcomes of IVF patients with abnormal vaginal microbiota: protocol for a double-blind, placebo-controlled multicentre trial
Authors: Haahr Thor , Freiesleben Nina La Cour , Pinborg Anja , Nielsen Henriette Svarre , Hartvig Vibeke , Mikkelsen Anne-Lis , Parks Thomas , Uldbjerg Niels , Jensen Jørgen Skov , Humaidan Peter
Published: October 2020

Introduction

Recent studies in in vitro fertilisation (IVF) patients have associated abnormal vaginal microbiota (AVM) with poor clinical pregnancy rates of 6%–9% per embryo transfer. The biological plausibility for this finding is hypothesised to be ascending infection to the endometrium which in turn hampers embryo implantation. New molecular based diagnosis may offer advantages compared to microscopical diagnosis of AVM which has huge inter-study variability ranging from 4 to 38%; however, the important question is whether screening and treatment of AVM would improve reproductive outcomes in IVF patients. Herein, we describe a protocol for an ongoing double-blind, placebo-controlled multicentre trial of IVF patients diagnosed with AVM and randomised in three parallel groups 1:1:1.

Methods and analysis

This is a drug intervention study where IVF patients will be screened for AVM, using a qPCR assay targeting Atopobium vaginae and Gardnerella vaginalis. If positive, patients will be randomised to one of the three study arms. The first arm consists of clindamycin 300 mg ×2 daily for 7 days followed by vaginal Lactobacillus crispatus CTV-05 until clinical pregnancy scan week 7–9. The second arm consists of clindamycin and placebo L. crispatus CTV-05, whereas patients in the third arm will be treated with placebo/placebo. We used a superiority design to estimate that active treatment in both arms will increase the primary outcome, clinical pregnancy rate per embryo transfer, from 20% to 40%. A potential difference between the two active arms was considered exploratory. With a power of 80% and an alpha at 5%, the sample size is estimated to be 333 patients randomised. A pre-planned interim analysis is scheduled at 167 patients randomised.

Ethics and dissemination

All patients have to give informed consent. Dissemination of results is ensured in clinical trial agreements whether they be positive or not. Ethics committee, Central Denmark Region approved this protocol.

Trial registration number

ICH-GCP monitored trial, EudraCT 2016-002385-31; Pre-results.
Digital telemedicine interventions for patients with multimorbidity: a systematic review and meta-analysis
Authors: Kraef Christian , van der Meirschen Marc , Free Caroline
Published: October 2020

Objective

To determine the effectiveness of digital telemedicine interventions designed to improve outcomes in patients with multimorbidity.

Design

Systematic review and meta-analysis of available literature.

Data sources

MEDLINE, EMBASE, The Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and the Database of Abstracts of Reviews of Effectiveness and hand searching. The search included articles from inception to 19 April 2019 without language restrictions. The search was updated on 7 June 2020 without additional findings.

Eligibility criteria

Prospective interventional studies reporting multimorbid participants employing interventions with at least one digital telemedicine component were included. Primary outcomes were patient physical or mental health outcomes, health-related quality of life scores and the utilisation of health services.

Results

Out of 5865 studies initially identified, 7 articles, reporting on 6 studies were retained (total of 699 participants). Four of these studies reported interventions including integration with usual care, two studies had interventions with no links to usual patient care. Follow-up periods lasted between 2 and 6 months. Among the studies with links to usual care, the primary outcomes were systolic blood pressure (SBP) (three studies), haemoglobin A1c (HbA1c) (three studies), total cholesterol (two studies) and self-perceived health status (one study). The evidence ranged from very low to moderate certainty. Meta-analysis showed a moderate decrease in SBP (8 mm Hg (95% CI 4.6 to 11.4)), a small to moderate decrease in HbA1c (0.46 mg/dL (95% CI 0.25 to 0.67)) and moderate decrease in total cholesterol (cholesterol 16.5 mg/dL (95% CI 8.1 to 25.0)) in the intervention groups. There was an absence of evidence for self-perceived health status. Among the studies with no links to usual care, time to hospitalisation (median time to hospitalisation 113.4 days intervention and 104.7 days control group, absolute difference 12.7 days) and the Minnesota Living with Heart Failure Questionnaire (intervention group 35.2 score points, control group 23.9 points, absolute difference 11.3, 95% CI 5.5 to 17.1) showed small reductions. The Personal Health Questionnaire (PHQ-8) showed no evidence of improvement (intervention 7.6 points, control 8.6 points, difference 1.0 points, 95% CI −22.9% to 11.9%).

Conclusion

Digital telemedicine interventions provided moderate evidence of improvements in measures of disease control but little evidence and no demonstrated benefits on health status. Further research is needed with clear descriptions of conditions, interventions and outcomes based on patients’ and healthcare providers’ preferences.

PROSPERO registration number

CRD42019134872.
Dance for people with chronic respiratory disease: a qualitative study
Authors: Philip Keir Elmslie James , Lewis Adam , Williams Sian , Buttery Sara Catherine , Polkey Michael I , Man William , Fancourt Daisy , Hopkinson Nicholas S
Published: October 2020

Objectives

To explore the experiences and perceived impact on health and well-being related to participation in a dance group for people with chronic respiratory disease (CRD).

Design

An exploratory qualitative study using thematic analysis of semistructured interviews.

Setting

A community dance group in a UK health centre.

Participants

Convenience sample of long-term dance group participants.

Intervention

Weekly community dance sessions designed for people with breathlessness, lasting 75 min, led by a trained community dance leader.

Results

Convenience sample of eight participants, six females, aged 57–87 years (mean 75), with a median 2-year attendance at weekly dance sessions. Long-term attendance was driven by strongly held beliefs regarding the health and well-being benefits of participation. Four key themes were identified: dance as (1) a holistically beneficial activity, with physical and psychosocial health benefits including improved or maintained physical fitness and psychological well-being, and reduced need for healthcare; (2) an integral part of their life; (3) an enjoyable activity; and (4) a source of deep social cohesion.

Conclusions

Dance group participants perceived a broad range of health benefits of relevance to the biopsychosocial impacts of their respiratory disease. The themes identified are useful in the ongoing planning and evaluation of dance as a holistic complex intervention for people with CRD. Further research is required to assess the extent of health impacts identified, and how dance might be most effectively placed as an option in the management of CRD.

Trial registration number

NCT04006015.
Factors associated with advanced stage at diagnosis of cervical cancer in Addis Ababa, Ethiopia: a population-based study
Authors: Dereje Nebiyu , Gebremariam Alem , Addissie Adamu , Worku Alemayehu , Assefa Mathewos , Abraha Aynalem , Tigeneh Wondemagegnehu , Kantelhardt Eva Johanna , Jemal Ahmedin
Published: October 2020

Objective

To describe the patterns and factors associated with advanced stage at diagnosis of cervical cancer among Addis Ababa residents, Ethiopia.

Design

A population-based cross-sectional study.

Setting

Seven major hospitals or diagnostic facilities in Addis Ababa, Ethiopia.

Participants

All histopathology-confirmed patients with incident cervical cancer diagnosed from 1 January 2017 to 30 June 2018 among Addis Ababa residents.

Outcome measures

The proportion of patients with cervical cancer diagnosed at early stage (stage I/II) and advanced stage (stage III/IV) of the disease according to International Federation of Gynaecology and Obstetrics staging criteria, and adjusted prevalence ratio (APR) for factors associated with advanced-stage diagnosis using a Poisson regression with robust variance model.

Results

The mean age of the study participants was 52.9 (±13.3) years. Nearly two-thirds (60.4%, 95% CI: 53.8% to 66.5%) of patients with cervical cancer were diagnosed at an advanced stage. Advanced stage at diagnosis was significantly associated with paying medical bill out of pocket (APR=1.44, 95% CI: 1.08 to 1.91), diagnostic interval >90 days (APR=1.31, 95% CI: 1.04 to 1.71), practicing religion as a remedy or not taking immediate action following symptom recognition (APR=1.25, 95% CI: 1.08 to 1.91) and visiting more than three different health facilities prior to diagnostic confirmation (APR=1.24, 95% CI: 1.07 to 1.51).

Conclusions

Our findings of the high proportion of advanced-stage diagnosis of cervical cancer in Addis Ababa and its strong associations with out-of-pocket medical bill, seeking care out of conventional medicine settings and multiple visits to healthcare facilities before diagnostic confirmations underscore the need for public policies to improve the affordability of cancer care and enhance community awareness about the severity of the disease and referral system, in addition to expanding cervical cancer screening.
Analysis of health administration data to inform health service planning for paediatric palliative care
Authors: Bowers Alison Pauline , Bradford Natalie , Chan Raymond Javan , Herbert Anthony , Yates Patsy
Published: October 2020

Background

Health service planning in paediatric palliative care is complex, with the diverse geographical and demographic characteristics adding to the challenge of developing services across different nations. Accurate and reliable data are essential to inform effective, efficient and equitable health services.

Aim

To quantify health service usage by children and young people aged 0–21 years with a life-limiting condition admitted to hospital and health service facilities in Queensland, Australia during the 2011 and 2016 calendar years, and describe the clinical and demographic characteristics associated with health services usage.

Design

Retrospective health administrative data linkage of clinical and demographic information with hospital admissions was extracted using International Statistical Classification of Diseases and Related Health Problems, Tenth Revision Australian Modification (ICD-10-AM) diagnostic codes. Data were analysed using descriptive statistics.

Setting/participants

Individuals aged 0–21 years with a life-limiting condition admitted to a Queensland Public Hospital and Health Service or private hospital.

Results

Hospital admissions increased from 17 955 in 2011 to 23 273 in 2016, an increase of 5318 (29.6%). The greatest percentage increase in admissions were for those aged 16–18 years (58.1%, n=1050), and those with non-oncological conditions (36.2%, n=4256). The greatest number of admissions by ICD-10-AM chapter for 2011 and 2016 were by individuals with neoplasms (6174, 34.4% and 7206, 31.0% respectively). Overall, the number of admissions by Indigenous children and young people increased by 70.2% (n=838).

Conclusions

Administrative data are useful to describe clinical and demographic characteristics and quantify health service usage. Available data suggest a growing demand for health services by children eligible for palliative care that will require an appropriate response from health service planners.