16 research outputs found
Initial value problem of the Whitham equations for the Camassa-Holm equation
No full textWe study the Whitham equations for the Camassa-Holm equation. The equations are neither strictly hyperbolic nor genuinely nonlinear. We are interested in the initial value problem of the Whitham equations. When the initial values are given by a step function, the Whitham solution is self-similar. When the initial values are given by a smooth function, the Whitham solution exists within a cusp in the x-t plane. On the boundary of the cusp, the Whitham equation matches the Burgers solution, which exists outside the cusp
Numerical study of aerosol dust behaviour in aspiration bunker
No full textThe information concerning dispersed composition and concentration of dust particles which are caught by local exhausts is necessary for scientific proved choice of dust retaining devices. To receive this information it is necessary to apply the stochastic [1] and determinate methods [2]. The last ones are based on the studying of single dust particles behavior and on the determination of maximum diameter of the caught particles or on the composition of their bordering trajectories. The main objective of this scientific paper is to work out the methods of dispersed composition prediction and dust concentration in extracting local exhausts air in the areas of arbitrary geometry taking into account vortical transitional currents which occur as a result of abrupt modification of area configuration. The mentioned method is based on the introduction of finite number of different fractions dust particles into the stream at every design moment of definite time period and on the tracing of their behavior until they are caught or precipitated. The stream of air current is designed on the basis of the method of discontinuous vortexes. Vortical transitional currents are formed as a result of current isolation from sharp edges of area border, and also from smooth surface on the spot of tangential gear constituent change. The program of air- and coal currents calculation near the local exhausts of different kinds is worked out. The concentration calculation and the design of dispersed dust composition in aspirated air of rotating cylinder-exhaust placed in aspirated cover is carried out. The geometric and kinematics parameters at which the minimum carry-over of dust particles into aspiration net are revealed. The worked out computer program allows to determine the most optimum geometric and aerodynamic properties of local exhausts in aspiration system. The conducted researches of air- and coal currents of such program allowed to state the scheme of energy-efficient aspiration cover with the functions of dust precipitation chamber
Book Reviews
No full textBook 1Book Title: Human PhysiologyBook Authors: B.J. Meyer, H.S. Meij & A. C. MeyerIllustrated. R113,00 01AT incl.). Kenwyn: Juta. 1994. ISBN 0-7021-2949-6.Book 2Book Title: The Urban Health Crisis: Strategies for Health for All in the Face of Rapid UrbanizationBook Author: W.H.O.Pp. xvi + 80. Sw.Fr.20,0/US18,00. Geneva: WHO. 1993. ISBN 92-4-156159-9.Book 3Book Title: A Guide for Epidemiological Studies of Oral Manifestations of HIV-InfectionBook Authors: S.L. Melnick, R. Nowjack-Raymer, D. V. Kleinman & P. A. SwangoPp. ix + 27. Sw.Fr.10,00. Geneva: WHO. 1993. ISBN 92-4-154453-8.Book 4Book Title: Neurological EmergenciesBook Author: R.A.C. Hughes (Ed.)Pp. viii + 357. Illustrated. £22,00. London: BMJ. 1994. ISBN 0-7279-0756-5.Book 5Book Title: Surrogate Motherhood: a Worldwide View of the IssuesBook Author: Diederika PretoriusPp. xxii + 219. 54,75. Illinois: Charles C. Thomas. 9194. ISBN 0-398-05787-7
Bioactive Phytochemicals from Coconut (Cocos nucifera) Oil Processing By-products
No full textThis chapter aims to evaluate the phytochemical compounds of the plant Cocos nucifera (L.) (coconut) and its by-products. Phytochemicals could be used as therapeutic agents and be produced via secondary metabolism in relatively small amounts. Many scientific studies show that carotenoids, phytoestrogens, nondigestible carbohydrates, flavonoids, and prebiotics significantly affect health. They reduce cancer risk due to phenolic antioxidants, anti-inflammatory effects, and dietary fibers. Due to the high utility and value of all the parts of the coconut plant and coconut plant coproducts, it has been used in many countries and cultures. Various applications have been performed on the nuts’ trunk, leaf, sheath, and outer shell, so there is probably no other crop of plant that can be compared to the coconut tree in terms of its versatile end uses. Furthermore, because of increasing demands for environmentally friendly and biodegradable agricultural products, coconut by-products such as coir and others are considered potential resources for current food and nonfood applications. This chapter summarizes the nutritional value, potential health benefits, and chemical composition of the various Cocos nucifera (L.) oil-processing by-products. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG
A PMUT based photoacoustic system as a microfluidic concentration detector
No full textWe report on the development of a novel piezo-MEMS-based optofluidic platform to detect the concentration of various species dissolved in a fluid. This platform employs piezoelectric micromachined ultrasound transducers (PMUTs) to work as a photoacoustic receiver, receiving ultrasound from fluid targets present in microfluidic channels while illuminated with a nanosecond pulsed laser. We fabricate both the PMUTs and the microfluidic channels and subsequently use them for the experiment. We also show the capability of PMUTs as a general photoacoustic receiver and demonstrate its signal-to-noise characteristics (31) and its wide fractional bandwidth (73%).Micro and Nano Engineerin
Bioactive Phytochemicals from Hemp (Cannabis sativa) Seed Oil Processing By-products
No full textCannabis is an industrial plant used in the food industry, green building industry, textile industry, cosmetic industry, and pharmaceutical industry. Hemp is an important food source that has been used for thousands of years. Technically a nut, hemp seeds contain significant amounts of fiber, lipids, protein (edestin and albumin), vitamins, tocopherols, and minerals. Hemp seed proteins are easily digested and contain all the essential amino acids in a nutritionally significant amount. Since hemp seed oil’s polyunsaturated fatty acids (PUFA) are over 80%, it is essential for human health. The fatty acids it contains are mostly linoleic acid and ?-linolenic acid. This is why hemp seed oil production has been increasing by processing oil from seeds. By-products from the oil processing process are used to enrich foods regarding the chemicals and nutritional values they contain. Hemp is a functional food because the use of seeds, oil, and the oil’s cake could be used in several industries. This chapter summarizes the chemical composition, nutritional value, and potential health benefits of hemp (Cannabis sativa) seed oil processing by-products. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG
Determination of the Local Heat Transfer Coefficient Using the Model of the Temperature Boundary Layer with the Convective Component in the Rotation Cavities of the LRE Turbopump
No full textЗуев Александр Александрович, кандидат технических наук, доцент кафедры «Двигатели летательных аппаратов», Сибирский государственный университет науки и технологий имени академика М.Ф. Решетнева, г. Красноярск, [email protected].
Пиунов Валерий Юрьевич, кандидат технических наук, заместитель директора АО «КБ химического машиностроения имени А.М. Исаева» - филиал АО «ГКНПЦ имени М.В. Хруничева», г. Королев, Московская область, [email protected].
Назаров Владимир Павлович; кандидат технических наук, профессор, заведующий кафедрой «Двигатели летательных аппаратов», Сибирский государственный университет науки и технологий имени академика М.Ф. Решетнева, г. Красноярск, [email protected].
Арнгольд Анна Анатольевна, начальник бюро спецсоединителей, приборов и пультов аппаратуры, АО «Красноярский машиностроительный завод», г. Красноярск, [email protected].
A.A. Zuev1, [email protected],
V.U. Piunov2, [email protected],
V.P. Nazarov1, [email protected],
A.A. Arngold3, [email protected]
1Siberian State University of Science and Technology named after M.F. Reshetnev, Krasnoyarsk, Russian Federation,
2A.M. Isayev Chemical Engineering Design Bureau - branch of Hrunichev State Research and Production Space Center, Korolyov, Moscow Region, Russian Federation,
3JSC “Krasnoyarsk machine-building plant”, Krasnoyarsk, Russian FederationУчет особенностей теплоотдачи в проточных частях турбонасосных агрегатов (ТНА) жидкостных ракетных двигателей (ЖРД) является важной задачей. Сопряженная задача течения с теплообменом, в том числе и при вращательных течениях в элементах проточных частей ТНА ЖРД, решается с помощью следующих подходов: численные методы, аналитическое совместное решение уравнений движения и энергии и использование эмпирических уравнений. Наличие теплообмена значительно влияет на рабочие характеристики ТНА ЖРД.
При проектировании проточных частей узлов и агрегатов ТНА ЖРД важно учитывать влияние теплообмена и как следствие - температуры потока рабочего тела по длине проточного тракта, в связи с тем, что вязкость напрямую зависит от температуры и определяет потери и режим течения.
В агрегатах подачи, особенно при использовании криогенных компонентов топлива, незначительный подогрев рабочего тела может привести к вскипанию компонентов и падению рабочих характеристик. С другой стороны, недостаточная (нерасчетная) температура компонента в проточной части для некоторых видов рабочих тел (например гелеобразных компонентов) приводит к повышенной вязкости и снижению КПД агрегата.
При исследовании задачи вращательных течений с теплообменом необходимо совместное решение уравнений движения и энергии в граничных условиях проточных частей ТНА ЖРД с учетом теории пространственного пограничного слоя.
Процессы теплоотдачи в энергетических установках во многом схожи, но при анализе и выводе уравнений теплообмена для граничных условий ЖРД существуют определенные отличия. Основные отличия заключаются в следующем: экстремально высокие значения тепловых потоков, температур и давлений, наличие высоких скоростей потоков, начальное турбулентное состояние потоков в активной зоне, рабочие тела могут находиться в газообразном и жидком состоянии, эффекты кривизны поверхности.
С использованием аналитического подхода определены уравнения для расчета локальных коэффициентов теплоотдачи в виде критериев Стантона для наиболее важных случаев, реализующихся при течении в полостях вращения ТНА ЖРД. Получены локальные коэффициенты теплоотдачи при прямолинейном течении, вращательных течениях, реализующихся в полостях между рабочим колесом и корпусом турбины и центробежного насоса (течение по закону твердого тела), в подводящих и отводящих аппаратах (течение по закону свободного вихря). Полученные аналитические выражения для локальных коэффициентов теплоотдачи хорошо согласуются с результатами исследований других авторов и имеют практическое применение при расчете характеристик тракта ТНА ЖРД.
An important research task is to take into account the features of heat transfer in turbine settings of turbopump units (TPU) of liquid rocket engines (LRE). The problem of heat transfer flow, including rotational flows in the elements of turbine settings of TPU LRE, is solved using the following approaches: numerical methods, analytical joint solution of equations of motion and energy, and using of empirical equations. Heat transfer significantly affects the performance characteristics of TPU LRE.
When designing the turbine settings of LRE assemblies and units, it is important to take into account the effect of heat transfer and, thus, the temperature of the working fluid flow along the length of the flow track. This is due to the fact that viscosity directly depends on temperature and determines the losses and flow pattern.
Slight heating of the working fluid can lead to boiling of its components and loss of performance characteristics in supply units, especially when using cryogenic components of fuel. On the other hand, insufficient (unplanned) temperature of a component in the turbine setting leads to increased viscosity of some working fluids (for example, gel-like components), and thus to reduced efficiency of the unit.
When studying the problem of rotational flows with heat transfer, it is necessary to solve the joint equations of motion and energy in the boundary conditions of LRE turbine settings, taking into account the theory of spatial boundary layer.
Heat transfer processes in power plants are in many ways similar, but there are certain differences in the analysis and derivation of heat transfer equations for the LRE boundary conditions. The main differences are as follows: extremely high values of heat flows, temperatures, and pressures; high flow velocities; initial turbulent state of the flows in the core; possible gaseous and liquid state of working fluids; surface curvature effects.
Using an analytical approach, we defined the equations for calculating local heat transfer coefficients in the form of Stanton criteria for the most important cases of flow in rotational cavities of TPU LRE. We obtained the local heat transfer coefficients for straight flow, rotational flows realized in the cavities between the impeller and the turbine casing and the centrifugal pump (solid state flow), in the inlet and outlet devices (free vortex). The obtained analytical expressions for the local heat transfer coefficients are consistent with the results of other author’ studies and may be applied in calculating the characteristics of an LRE turbopump track
Evidence for massive and recurrent toxic blooms of Alexandrium catenella in the Alaskan Arctic
No full text© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Anderson, D. M., Fachon, E., Pickart, R. S., Lin, P., Fischer, A. D., Richlen, M. L., Uva, V., Brosnahan, M. L., McRaven, L., Bahr, F., Lefebvre, K., Grebmeier, J. M., Danielson, S. L., Lyu, Y., & Fukai, Y. Evidence for massive and recurrent toxic blooms of Alexandrium catenella in the Alaskan Arctic. Proceedings of the National Academy of Sciences of the United States of America, 118(41) (2021): e2107387118, https://doi.org/10.1073/pnas.2107387118.Among the organisms that spread into and flourish in Arctic waters with rising temperatures and sea ice loss are toxic algae, a group of harmful algal bloom species that produce potent biotoxins. Alexandrium catenella, a cyst-forming dinoflagellate that causes paralytic shellfish poisoning worldwide, has been a significant threat to human health in southeastern Alaska for centuries. It is known to be transported into Arctic regions in waters transiting northward through the Bering Strait, yet there is little recognition of this organism as a human health concern north of the Strait. Here, we describe an exceptionally large A. catenella benthic cyst bed and hydrographic conditions across the Chukchi Sea that support germination and development of recurrent, locally originating and self-seeding blooms. Two prominent cyst accumulation zones result from deposition promoted by weak circulation. Cyst concentrations are among the highest reported globally for this species, and the cyst bed is at least 6× larger in area than any other. These extraordinary accumulations are attributed to repeated inputs from advected southern blooms and to localized cyst formation and deposition. Over the past two decades, warming has likely increased the magnitude of the germination flux twofold and advanced the timing of cell inoculation into the euphotic zone by 20 d. Conditions are also now favorable for bloom development in surface waters. The region is poised to support annually recurrent A. catenella blooms that are massive in scale, posing a significant and worrisome threat to public and ecosystem health in Alaskan Arctic communities where economies are subsistence based.Funding for D.M.A., R.S.P., E.F., P.L., A.D.F., V.U., M.L.B., L.M., F.B., and M.L.R. was provided by grants from the NSF Office of Polar Programs (Grants OPP-1823002 and OPP-1733564) and the National Ocanic and Atmospheric Administration (NOAA) Arctic Research program (through the Cooperative Institute for the North Atlantic Region [CINAR; Grants NA14OAR4320158 and NA19OAR4320074]), for J.M.G. through CINAR 22309.07 UMCES (University of Maryland Center for Environmental Science), and for D.M.A. and K.L. through NOAA’s Center for Coastal and Ocean Studies Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) Program (NA20NOS4780195). Funding for D.M.A., M.L.R., M.L.B., E.F., V.U., and A.D.F. was also provided by NSF (Grant OCE-1840381) and NIH (Grant 1P01-ES028938-01) through the Woods Hole Center for Oceans and Human Health. S.L.D. was supported by North Pacific Research Board IERP Grants A91-99a and A91-00a. This is IERP publication ArcticIERP-41 and ECOHAB Contribution No. ECO983
Life cycles and feeding habits of Syngnathus taenionotus and S. abaster (Pisces, Syngnathidae) in a brackish bay of the Po River Delta (Adriatic Sea).
No full textThese species inhabit the nearshore environment of the bay where the sandy bottom is covered by macroalgae. The main differences in life history traits between S. taenionotus and S. abaster respectively can be summarized as follows: life span is c24 vs 17 mo; reproductive season begins in February vs March, and lasts 5 vs 4 mo; average length of fingerlings at the time they hatch from the male brood pouch is 20.3(±1.2) vs 13.5(±1.0) mm; egg incubation period is 2 mo vs 1 mo; average number of ripe eggs per mature ovary is 46(±9) vs 104(±40); average number of embryos incubated by male is 84(±17) vs 109(±27). The sex ratio in the reproductive population is more male-biased in S. taenionotus. The two species probably do not compete for food resources, remaining almost completely segregated in different foraging micro-habitats during most of their life span. The new-born spring individuals of both species feed almost exclusively on harpacticoids of the genus Tisbe. As they mature, S. abaster continue to prey on phytal organisms while the larger S. taenionotus become zooplanktivorous. -from Author
Gas-phase electrophoresis (nES GEMMA instrumentation) of adeno-associated viruses
No full textGas-phase electrophoresis (nES GEMMA instrumentation) of adeno-associated viruses
S. Zoratto1, T. Heuser2, G. Friedbacher1, R. Pletzenauer3, M. Graninger3,
M. Marchetti-Deschmann1, and V.U. Weiss1
1Institute of Chemical Technologies and Analytics, TU Wien, Vienna, 1060, Austria
2Electron Microscopy Facility, Vienna BioCenter Core Facilities GmbH, Vienna, 1030, Austria
3Pharmaceutical Sciences, Baxalta Innovations GmbH (part of Takeda), Vienna, 1220, Austria
Keywords: nES GEMMA, DMA, AAV, VLP, gas-phase electrophoresis.
Associated conference topics: Special session, 3.4, 4.3
Presenting author email: [email protected]
In 1996, Kaufman et al. introduced electrophoresis in the gas-phase on a nano Electrospray Gas-phase Electrophoretic Mobility Molecular Analyzer (nES GEMMA) aka nES Differential Mobility Analyzer (nES DMA) for globular proteins. (Kaufman, 1996) With such an instrument, analytes are electrosprayed from a volatile electrolyte solution followed by drying of droplets and charge equilibration in a bipolar atmosphere induced e.g. by a radioactive source. Lately, also an alternating bipolar corona discharge was applied for this process. (Weiss, 2020) Single-charged, aerosolized and surface-dry analytes are separated according to their size in a DMA. The obtained monodisperse particles are then counted in a condensation particle counter yielding a spectrum relating a particles surface dry diameter (electrophoretic mobility, EM, diameter) to particle count values.
Subsequently, this technique was applied also to other (bio-)nanoparticles, i.a. viruses and virus-like particles (VLPs). (Bacher, 2001 and Weiss, 2019). Via a nES GEMMA setup, information on (bio-)nanoparticle size and size distribution as well as purity of analyte batches can be obtained. Furthermore, by application of a corresponding EM diameter / molecular weight correlation, the molecular weight of an analyte can be assessed from gas-phase electrophoresis data.
Turning our attention to VLP based delivery platforms, we investigated gas-phase electrophoresis of an adeno-associated virus (Zoratto, 2021a). Indeed we were able to obtain corresponding spectra. However, we found conditions of the nES crucial for data quality. Presence of VLPs in samples was affirmed by atomic force microscopy (AFM).
Figure 1. nES GEMMA spectrum of AAV VLPs (red line) and a corresponding blank (black line) – left. Presence of VLPs was confirmed via AFM measurements – right. (from Zoratto, 2021a)
Subsequently, the molecular weight of AAV VLPs was assessed based on gas-phase electrophoresis data. We found these obtained values in excellent accordance with data derived from mass spectrometry. (Zoratto, 2021b)
Table 1. Molecular weight values of AAV VLPs obtained via indicated techniques (Zoratto, 2021b).
Molecular weight [kDa] Empty VLPs Filled
VLPs
Theoretical value 3746 5076
nES GEMMA 3670 4751
Native MS 3710 5005
To conclude, gas-phase electrophoresis is capable to yield valuable information in the field of (bio-)nanoparticle characterization – from particle size to VLP molecular weight values as exemplified via AAV based VLPs.
We dedicate this presentation to the memory of Prof. Günter Allmaier, TU Wien, Vienna, Austria.
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Zoratto S, Weiss VU, van der Horst J et al. (2021) J Mass Spectrom 56, e478
