88 research outputs found
Scenario-based earthquake hazard and risk assessment for Baku (Azerbaijan)
A rapid growth of population, intensive civil and industrial building, land and water instabilities (e.g. landslides, significant underground water level fluctuations), and the lack of public awareness regarding seismic hazard contribute to the increase of vulnerability of Baku (the capital city of the Republic of Azerbaijan) to earthquakes. In this study, we assess an earthquake risk in the city determined as a convolution of seismic hazard (in terms of the surface peak ground acceleration, PGA), vulnerability (due to building construction fragility, population features, the gross domestic product per capita, and landslide's occurrence), and exposure of infrastructure and critical facilities. The earthquake risk assessment provides useful information to identify the factors influencing the risk. A deterministic seismic hazard for Baku is analysed for four earthquake scenarios: near, far, local, and extreme events. The seismic hazard models demonstrate the level of ground shaking in the city: PGA high values are predicted in the southern coastal and north-eastern parts of the city and in some parts of the downtown. The PGA attains its maximal values for the local and extreme earthquake scenarios. We show that the quality of buildings and the probability of their damage, the distribution of urban population, exposure, and the pattern of peak ground acceleration contribute to the seismic risk, meanwhile the vulnerability factors play a more prominent role for all earthquake scenarios. Our results can allow elaborating strategic countermeasure plans for the earthquake risk mitigation in the Baku city
Scenario-based earthquake hazard and risk assessment for Baku (Azerbaijan)
A rapid growth of population, intensive civil and industrial building, land and water instabilities (e.g. landslides, significant underground water level fluctuations), and the lack of public awareness regarding seismic hazard contribute to the increase of vulnerability of Baku (the capital city of the Republic of Azerbaijan) to earthquakes. In this study, we assess an earthquake risk in the city determined as a convolution of seismic hazard (in terms of the surface peak ground acceleration, PGA), vulnerability (due to building construction fragility, population features, the gross domestic product per capita, and landslide’s occurrence), and exposure of infrastructure and critical facilities. The earthquake risk assessment provides useful information to identify the factors influencing the risk. A deterministic seismic hazard for Baku is analysed for four earthquake scenarios: near, far, local, and extreme events. The seismic hazard models demonstrate the level of ground shaking in the city: PGA high values are predicted in the southern coastal and northeastern parts of the city and in some parts of the downtown. The PGA attains its maximal values for the local and extreme earthquake scenarios. We show that the quality of buildings and the probability of their damage, the distribution of urban population, exposure, and the pattern of peak ground acceleration contribute to the seismic risk, meanwhile the vulnerability factors play a more prominent role for all earthquake scenarios. Our results can allow elaborating strategic countermeasure plans for the earthquake risk mitigation in the Baku city
Hydrogen double compression-expansion engine (H2DCEE): A sustainable internal combustion engine with 60%+ brake thermal efficiency potential at 45 bar BMEP
Hydrogen (H-2) internal combustion engines may represent cost-effective and quick solution to the issue of the road transport decarbonization. A major factor limiting their competitiveness relative to fuel cells (FC) is the lower efficiency. The present work aims to demonstrate the feasibility of a H-2 engine with FC-like 60%+ brake thermal efficiency (BTE) levels using a double compression-expansion engine (DCEE) concept combined with a high pressure direct injection (HPDI) nonpremixed H-2 combustion. Experimentally validated 3D CFD simulations are combined with 1D GT-Power simulations to make the predictions. Several modifications to the system design and operating conditions are systematically implemented and their effects are investigated. Addition of a catalytic burner in the combustor exhaust, insulation of the expander, dehumidification of the EGR, and removal of the intercooling yielded 1.5, 1.3, 0.8, and 0.5%-point BTE improvements, respectively. Raising the peak pressure to 300 bar via a larger compressor further improved the BTE by 1.8%-points but should be accompanied with a higher injector-cylinder differential pressure. The lambda of ~1.4 gave the optimum tradeoff between the mechanical and combustion efficiencies. A peak BTE of 60.3% is reported with H2DCEE, which is ~5%-points higher than the best diesel-fueled DCEE alternative
Computational comparison of the conventional diesel and hydrogen direct-injection compression-ignition combustion engines
Most research and development on hydrogen (H2) internal combustion engines focus on premixed-charge spark ignition (SI) or diesel-hydrogen dual-fuel technologies. Premixed charge limits the engine efficiency, power density, and safety, while diesel injections give rise to CO2 and particulate emissions. This paper demonstrates a non-premixed compression-ignition (CI) neat H2 engine concept that uses H2 pilots for ignition. It compares the CI H2 engine to an equivalent diesel engine to draw fundamental insights about the mixing and combustion processes. The Converge computational fluid dynamics solver is used for all simulations. The results show that the brake thermal efficiency of the CI H2 engine is comparable or higher than diesel, and the molar expansion with H2 injections at TDC constitutes 5–10 % of the total useful work. Fuel-air mixing in the free-jet phase of combustion is substantially higher with H2 due to hydrogen\u27s gaseous state, low density, high injection velocity, and transient vortices, which contribute to the 3 times higher air entrainment into the quasi-steady-state jet regions. However, the H2 jet momentum is up to 4 times lower than for diesel, which leads to not only ineffective momentum-driven global mixing but also reduced heat transfer losses with H2. The short H2 flame quenching distance may also be inconsequential for heat transfer in CI engines. Finally, this research enables future improvements in CI H2 engine efficiency by hypothesizing a new optimization path, which maximizes the free-jet phase of combustion, hence is totally different from that for conventional diesel engines
Double compression-expansion engine (DCEE) fueled with hydrogen: Preliminary computational assessment
Hydrogen (H2) is currently a highly attractive fuel for internal combustion engines (ICEs) owing to the prospects of potentially near-zero emissions. However, the production emissions and cost of H2 fuel necessitate substantial improvements in ICE thermal efficiency. This work aims to investigate a potential implementation of H2 combustion in a highly efficient double compression-expansion engine (DCEE). DICI nonpremixed H2 combustion mode is used for its superior characteristics, as concluded in previous studies. The analysis is performed using a 1D GT-Power software package, where different variants of the DICI H2 and diesel combustion cycles, obtained experimentally and numerically (3D CFD) are imposed in the combustion cylinder of the DCEE. The results show that the low jet momentum, free jet mixing dominated variants of the DICI H2 combustion concept are preferred, owing to the lower heat transfer losses and relaxed requirements on the fuel injection system. Insulation of the expander and removal of the intercooling improve the engine efficiency by 1.3 and 0.5%-points, respectively, but the latter leads to elevated temperatures in the high-pressure tank, which makes the selection of its materials harder but allows the use of cheaper oxidation catalysts. The results also show that the DCEE performance is insensitive to combustion cylinder temperatures, making it potentially suitable for other high-octane fuels, such as methane, methanol, ammonia, etc. Finally, a brake thermal efficiency of 56% is achieved with H2 combustion, around 1%-point higher than with diesel. Further efficiency improvements are also possible with a fully optimized H2 combustion system
Effect of elevated NaCl concentration to the photosynthesis and activity of catalase in Dunaliella salina cells
Исследовано влияние повышение концентрации NaCl (от 0,5 до 4,0 м) на пигментный состав, кислородный обмен и активность каталазы клеток зеленой водоросли Dunaliella salina. Установлено оптимальную концентрацию NaCl (2,0 М), при которой отмечено интенсивное биосинтез зеленых пигментов и функционирования фотосинтетического аппарата. При повышенных концентрациях NaCl (3,0 и 4,0 м) растет активность каталазы в 5,8 раза в пересчете на 1 мг белка по сравнению с контролем, что составляло 0,5703 мкмоль / мин. на мг белка. Активность каталазы может быть использована как показатель устойчивости клеток водоросли в условиях солевого стрессаДосліджено вплив підвищення концентрації NaCl (від 0,5 до 4,0 М) на пігментний склад, кисневий обмін і активність каталази клітин зеленої водорості Dunaliella salina. Встановлено оптимальну концентрацію NaCl (2,0 М), за якої відмічено інтенсивний біосинтез зелених пігментів і функціонування фотосинтетичного апарату. При підвищених концентраціях NaCl (3,0 та 4,0 М) зростає активність каталази у 5,8 раза у перерахунку на 1 мг білка порівняно з контролем, що становило 0,5703 мкмоль/хв. на мг білка. Активність каталази може бути використана як показник стійкості клітин водорості до умов сольового стресуThe effect of elevated NaCl concentration (from 0.5 to 4.0 M) to the pigment content, O2 exchange and activities of some oxidative stress enzymes in the green alga Dunaliella salina was investigated. The optimum NaCl concentration (2.0 M) for the intensive biosynthesis of green pigments and function of the photosynthetic apparatus were established. The catalase activity increased up to 5.8 times and reached 0.5703 µmol min-1mg-1protein after 7 days of exposure to high salt concentration (3.0 and 4.0 M). The activity of catalase can be used as an indicator of alga cells’ resistance to salinity stress
Negative magneto-resistance of electron gas in a quantum well with parabolic potential
We have studied the electrical conductivity of the electron gas in parallel
electric and magnetic fields directed along the plane of a parabolic quantum
well (across the profile of the potential). We found a general expression for
the electrical conductivity applicable for any magnitudes of the magnetic field
and the degree of degeneration of the electron gas. A new mechanism of
generation of the negative magnetoresistance has been revealed. It has been
shown that in a parabolic quantum well with a non-degenerated electron gas the
negative magnetoresistance results from spin splitting of the levels of the
size quantization.Comment: 15 pages, 3 figure
Some peculiarities of water regime and photosynthetic capasity of wheat genotypes under drought conditions
Досліджено особливості водного режиму, вмісту білка та фотосинтетичну здатність хлоропластів у листі генотипів пшениці в умовах посухи. Виявлено, що стабільність фотосинтетичної здатності хлоропластів стійкого генотипу зумовлена високим відносним вмістом води, низьким водним дефіцитом і високим вмістом білка у листі протягом періоду посухиИсследованы особенности водного режима, содержания белка и фотосинтетическая способность хлоропластов в письме генотипов пшеницы в условиях засухи. Выявлено, что стабильность фотосинтетической способности хлоропластов устойчивого генотипа обусловлена высоким относительным содержанием воды, низким водным дефицитом и высоким содержанием белка в письме в течение периода засухиThe peculiarities of water regime, protein content and photosynthetic capacity of chloroplasts in the leaves of wheat of the different genotypes have been investigated under drought conditions. It was established that the stability of photosynthetic capacity of chloroplasts of a tolerant genotype is stipulated by high relative water content, low water deficit and high protein content in leaves during the drought perio
Menstruation: science and society
© 2020 The Authors Women\u27s health concerns are generally underrepresented in basic and translational research, but reproductive health in particular has been hampered by a lack of understanding of basic uterine and menstrual physiology. Menstrual health is an integral part of overall health because between menarche and menopause, most women menstruate. Yet for tens of millions of women around the world, menstruation regularly and often catastrophically disrupts their physical, mental, and social well-being. Enhancing our understanding of the underlying phenomena involved in menstruation, abnormal uterine bleeding, and other menstruation-related disorders will move us closer to the goal of personalized care. Furthermore, a deeper mechanistic understanding of menstruation—a fast, scarless healing process in healthy individuals—will likely yield insights into a myriad of other diseases involving regulation of vascular function locally and systemically. We also recognize that many women now delay pregnancy and that there is an increasing desire for fertility and uterine preservation. In September 2018, the Gynecologic Health and Disease Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development convened a 2-day meeting, “Menstruation: Science and Society” with an aim to “identify gaps and opportunities in menstruation science and to raise awareness of the need for more research in this field.” Experts in fields ranging from the evolutionary role of menstruation to basic endometrial biology (including omic analysis of the endometrium, stem cells and tissue engineering of the endometrium, endometrial microbiome, and abnormal uterine bleeding and fibroids) and translational medicine (imaging and sampling modalities, patient-focused analysis of menstrual disorders including abnormal uterine bleeding, smart technologies or applications and mobile health platforms) to societal challenges in health literacy and dissemination frameworks across different economic and cultural landscapes shared current state-of-the-art and future vision, incorporating the patient voice at the launch of the meeting. Here, we provide an enhanced meeting report with extensive up-to-date (as of submission) context, capturing the spectrum from how the basic processes of menstruation commence in response to progesterone withdrawal, through the role of tissue-resident and circulating stem and progenitor cells in monthly regeneration—and current gaps in knowledge on how dysregulation leads to abnormal uterine bleeding and other menstruation-related disorders such as adenomyosis, endometriosis, and fibroids—to the clinical challenges in diagnostics, treatment, and patient and societal education. We conclude with an overview of how the global agenda concerning menstruation, and specifically menstrual health and hygiene, are gaining momentum, ranging from increasing investment in addressing menstruation-related barriers facing girls in schools in low- to middle-income countries to the more recent “menstrual equity” and “period poverty” movements spreading across high-income countries
Menstruation: science and society
© 2020 The Authors Women's health concerns are generally underrepresented in basic and translational research, but reproductive health in particular has been hampered by a lack of understanding of basic uterine and menstrual physiology. Menstrual health is an integral part of overall health because between menarche and menopause, most women menstruate. Yet for tens of millions of women around the world, menstruation regularly and often catastrophically disrupts their physical, mental, and social well-being. Enhancing our understanding of the underlying phenomena involved in menstruation, abnormal uterine bleeding, and other menstruation-related disorders will move us closer to the goal of personalized care. Furthermore, a deeper mechanistic understanding of menstruation—a fast, scarless healing process in healthy individuals—will likely yield insights into a myriad of other diseases involving regulation of vascular function locally and systemically. We also recognize that many women now delay pregnancy and that there is an increasing desire for fertility and uterine preservation. In September 2018, the Gynecologic Health and Disease Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development convened a 2-day meeting, “Menstruation: Science and Society” with an aim to “identify gaps and opportunities in menstruation science and to raise awareness of the need for more research in this field.” Experts in fields ranging from the evolutionary role of menstruation to basic endometrial biology (including omic analysis of the endometrium, stem cells and tissue engineering of the endometrium, endometrial microbiome, and abnormal uterine bleeding and fibroids) and translational medicine (imaging and sampling modalities, patient-focused analysis of menstrual disorders including abnormal uterine bleeding, smart technologies or applications and mobile health platforms) to societal challenges in health literacy and dissemination frameworks across different economic and cultural landscapes shared current state-of-the-art and future vision, incorporating the patient voice at the launch of the meeting. Here, we provide an enhanced meeting report with extensive up-to-date (as of submission) context, capturing the spectrum from how the basic processes of menstruation commence in response to progesterone withdrawal, through the role of tissue-resident and circulating stem and progenitor cells in monthly regeneration—and current gaps in knowledge on how dysregulation leads to abnormal uterine bleeding and other menstruation-related disorders such as adenomyosis, endometriosis, and fibroids—to the clinical challenges in diagnostics, treatment, and patient and societal education. We conclude with an overview of how the global agenda concerning menstruation, and specifically menstrual health and hygiene, are gaining momentum, ranging from increasing investment in addressing menstruation-related barriers facing girls in schools in low- to middle-income countries to the more recent “menstrual equity” and “period poverty” movements spreading across high-income countries
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