1,299 research outputs found
Scientific Substantiation of the Methodology of Preparation of Quince Japanese for Analysis and Investigation of Consumer Properties of the Products of Its Recycling
The aim of the study is a scientific substantiation of the methodology of quince Japanese for analyzing and investigating consumer properties of its recycling products. The new way of sample preparation allows to reduce costs for estimation of the raw material quality. Obtained semi-products give a possibility to widen the assortment of frozen products, based on domestic raw materials.Fruits of quince Japanese, planted in the Poltava region, Ukraine, were chosen as a research object. For getting a representing sample, quince specimens were subjected to the offered sample preparation. It included inspection, processing and further cyclic freezing and centrifuging. As a result of the threefold cycle of freezing-centrifuging, solid and liquid phases were obtained.The obtained liquid part of quince Japanese is a homogenous liquid, without suspended particles, with a brightly expressed taste and smell, not stratified at storage. These changes are explained by redistribution of dry substances and moisture in studied samples.As a result of cyclic freezing-centrifuging of the research object, two new semi-products were obtained – solid and liquid phases.Within the scientific study there were determined organoleptic parameters of the obtained semi-products before freezing and after 270 days of low-temperature storage. The consistence, taste, smell and color of products are ones of their main consumption properties.According to the results of point estimation of organoleptic properties of the obtained semi-products, it has been established, that during 270 days of low-temperature storage these parameters didn\u27t change and stayed at the high level.The studies demonstrated freezing advantages in the aspect of reaching high organoleptic parameters of products after freezing and defrost that provides high-quality products in the process of low-temperature storage
The Study of Thermal Reversibility of the Freezing-defrost Process of Browned Onion
The features and dynamics of the freezing-defrost processes of the studied sample of browned onion were established and studied. At the research it was revealed, that at freezing temperature –20 °С the value of maximal freezing speed does not change.The process of defrost of browned onion was carried out using calorimeter with the reverse connection on temperature and PID-regulator, on the temperature curve of its freezing. It was determined, that the process of defrost of the studied sample needs more heat that is educed at freezing. The modes of stepped defrost that testify to the possibility of thermal reversibility of freezing process were experimentally established.The direct dependence of educed and consumed heat quantity on the mode of thermal processing of studied sample was revealed. The more moisture was eliminated from the food product, the less heat must be consumed for defrost. The analogous dependence is typical also for the freezing process.The received data can be used for determination of the rational modes of freezing and defrost of the browned onion
The results of magnetic separation use in ore processing of metalliferous raw basalt of Volyn region
Purpose. To determine the effectiveness of the electric field use in ore processing for extraction of native copper concentrate from raw basalt, to identify the most technologically advanced grain-size classes of the feed stock. To define the nature of the relationship between the amount of recoverable concentrate and the main dominant factors – separator field density and the coarseness of the prepared raw material.
Methods. We used the substantiated physical and chemical methods of elemental, mineral, fractional, particle size distribution analysis of the basalt rock mass under processing, methods of laboratory, semi-industrial and industrial research into crushing, grinding, classification, and electromagnetic separation processes at the stages of ore preparation of raw materials for the production of metalliferous industrial products. The methods of statistical modeling and experimental results regression analysis have been applied.
Findings. The preferred grain-size classes in the process of ore preparation and classification of basalt rock components for electrostatic separation were determined. The dependences of copper concentrate production from basalt, tuff and lava-breccia on the electrostatic field density while changing grain-size classes in the initial product were worked out. The regression dependences of the copper concentrate output on various relationships between grain-size classes in the initial material and the electric field density were obtained.
Originality. The content of native copper in basalt, lava breccia and tuff was established and the preferred grain-size classes in the process of ore preparation were identified. It is for the first time that the magnetic susceptibility of all three components of basalt raw material was determined, and the influence of the magnetic field on the output of titano-magnetite concentrate was shown as well as the rational grain size of ore preparation was detrmined. The
dependences of the copper concentrate output have been established and the efficiency of the electrical separation in complex processing of basalt raw material has been proved.Мета. Визначення ефективності використання електричного поля у процесі рудопідготовки для виділення концентрату самородної міді з базальтової сировини, встановлення найбільш технологічних класів крупності перероблюваної сировини й характеру залежності кількості добутого концентрату від основних домінуючих факторів – напруженості поля сепаратора та крупності підготовленої сировини.
Методика. У роботі використані апробовані фізичні та хімічні методи аналізу елементного, мінерального, фракційного, гранулометричного складу переробки базальтової гірської маси, методи лабораторних, напівпромислових і промислових досліджень процесів дроблення, подрібнення, класифікації, електромагнітної сепарації на етапах рудопідготовки сировини до отримання металовмісних промпродуктів. Застосовані методи статистичного моделювання і регресійного аналізу результатів експериментальних досліджень.
Результати. Встановлено класи крупності у процесі рудопідготовки і класифікації складових базальтової гірської маси до електросепарації. Виявлено залежності виходу мідного концентрату для базальту, туфу та лавобрекчії від напруженості електричного поля при варіюванні вмістом різних класів крупності у вихідному продукті. Отримано регресійні залежності виходу мідного концентрату від різних співвідношень між класами крупності у вихідному продукті та від напруженості електричного поля.
Наукова новизна. Встановлено процентний вміст самородної міді у базальті, лавобрекчії, туфі та показані кращі класи крупності у процесі рудопідготовки. Вперше визначена магнітна сприйнятливість всіх трьох складових базальтової сировини, показано вплив величини магнітного поля на вихід концентрату титаномагнетиту й визначена раціональна крупність рудопідготовки. Вперше встановлено залежності виходу мідного концентрату й показана ефективність використання операції електричної сепарації при комплексній переробці базальтової сировини.
Практична значимість. Отримані результати досліджень вказують на доцільність комплексної переробки базальтової сировини, і на цій основі розроблений спосіб її переробки.Цель. Определение эффективности использования электрического поля в процессе рудоподготовки для выделения концентрата самородной меди из базальтового сырья, установление наиболее технологичных классов крупности перерабатываемого сырья и характера зависимости количества извлекаемого концентрата от основных доминирующих факторов – напряженности поля сепаратора и крупности подготовленного сырья.
Методика. В работе использованы апробированные физические и химические методы анализа элементного, минерального, фракционного, гранулометрического состава перерабатываемой базальтовой горной массы, методы лабораторных, полупромышленных и промышленных исследований процессов дробления, измельчения, классификации, электромагнитной сепарации на этапах рудоподготовки сырья к получению металлосодержащих промпродуктов. Применены методы статистического моделирования и регрессионного анализа результатов экспериментальных исследований.
Результаты. Установлены предпочтительные классы крупности в процессе рудоподготовки и классификации составляющих базальтовой горной массы к электросепарации. Установлены зависимости выхода медного концентрата для базальта, туфа и лавобрекчии от напряженности электрического поля при варьировании содержанием разных классов крупности в исходном продукте. Получены регрессионные зависимости выхода медного концентрата от различных соотношений между классами крупности в исходном продукте и от напряженности электрического поля.
Научная новизна. Установлено процентное содержание самородной меди в базальте, лавобрекчии и туфе, а также показаны предпочтительные классы крупности в процессе рудоподготовки. Впервые установлена магнитная восприимчивость всех трех составляющих базальтового сырья, показано влияние величины магнитного поля на выход концентрата титаномагнетита и определена рациональная крупность рудоподго-товки. Впервые установлены зависимости выхода медного концентрата и показана эффективность использования операции электрической сепарации при комплексной переработке базальтового сырья.
Практическая значимость. Полученные результаты исследований указывают на целесообразность комплексной переработки базальтового сырья, и на этой основе разработан способ его переработки
Impurity effects on the melting of Ni clusters
We demonstrate that the addition of a single carbon impurity leads to
significant changes in the thermodynamic properties of Ni clusters consisting
of more than a hundred atoms. The magnitude of the change induced is dependent
upon the parameters of the Ni-C interaction. Hence, thermodynamic properties of
Ni clusters can be effectively tuned by the addition of an impurity of a
particular type. We also show that the presence of a carbon impurity
considerably changes the mobility and diffusion of atoms in the Ni cluster at
temperatures close to its melting point. The calculated diffusion coefficients
of the carbon impurity in the Ni cluster can be used for a reliable estimate of
the growth rate of carbon nanotubes.Comment: 27 pages, 13 figure
Influence of Kerr nonlinearity on PT-transition in coupled fibre lasers
This work investigates a concept of coupled fiber lasers exhibiting PT-symmetry and a PT-transition between PTsymmetric and PT-broken lasing states. We consider a system operated via Raman gain comprising two fiber loops (ring cavities) connected to each other by means of two fiber couplers with adjustable phase shift between them. By changing the phase shift or/and amplification (loss) in fiber loops, one can switch between generation regimes, realizing either PTsymmetric or PT-broken solution. In the PT-symmetric lasing regime, equal powers are generated in both cavities despite only active one is pumped. We make theoretical and numerical description of the proposed coupled fiber lasers starting with the simple discrete matrix model taking into account coupling, phase delays, gain (which is assumed to be saturated), losses and nonlinear phase shift. We show how the PT-transition is affected by self-phase modulation inside the fiber cavity and investigate requirements that should be met in order to observe PT-transition experimentally despite Kerr effect that violates exact symmetry conditions. In particular, we show that PT-transition may be observable only near lasing threshold. Further on we adopt more sophisticated model based on Nonlinear Schrödinger equation for PT fiber laser. Taking into account quasi-CW polychromatic radiation with typical spectral bandwidth of fiber Raman lasers, chromatic dispersion and Kerr nonlinearity, we demonstrate both PT-symmetric and PT-broken lasing in a fiber laser
Alternative pathways of dewetting for a thin two-layer film of soft matter
We consider two stacked ultra-thin layers of different liquids on a solid
substrate. Using long-wave theory, we derive coupled evolution equations for
the free liquid-liquid and liquid-gas interfaces. Linear and non-linear
analyses show that depending on the long-range van-der-Waals forces and the
ratio of the layer thicknesses, the system follows different pathways of
dewetting. The instability may be driven by varicose or zigzag modes and leads
to film rupture either at the liquid-gas interface or at the substrate
Electronic Band Structure In A Periodic Magnetic Field
We analyze the energy band structure of a two-dimensional electron gas in a
periodic magnetic field of a longitudinal antiferromagnet by considering a
simple exactly solvable model. Two types of states appear: with a finite and
infinitesimal longitudinal mobility. Both types of states are present at a
generic Fermi surface. The system exhibits a transition to an insulating regime
with respect to the longitudinal current, if the electron density is
sufficiently low.Comment: 8 pages, 5 figures; to appear in Phys. Rev. B '9
On the Thermal History of Calculable Gauge Mediation
Many messenger models with realistic gaugino masses are based on meta-stable
vacua. In this work we study the thermal history of some of these models.
Analyzing R-symmetric models, we point out that while some of the known
messenger models clearly prefer the supersymmetric vacuum, there is a vast
class of models where the answer depends on the initial conditions. Along with
the vacuum at the origin, the high temperature thermal potential also possesses
a local minimum far away from the origin. This vacuum has no analog at zero
temperature. The first order phase transition from this vacuum into the
supersymmetric vacuum is parametrically suppressed, and the theory, starting
from that vacuum, is likely to evolve to the desired gauge-mediation vacuum. We
also comment on the thermal evolution of models without R-symmetry.Comment: 22 pages. V2: Comments on the SM effects added. Minor corrections.
Reference added. Valuable discussion with S. Abel, J. Jaeckel and V. Khoze
acknowledged. V3: Types of EOGM explicitly defined in the introduction.
Discussions about the phase transitions expanded. Typo corrected. Journal
versio
Kinetic behavior of Desulfovibrio gigas aldehyde oxidoreductase encapsulated in reverse micelles
Biochemical and Biophysical Research Communications 308 (2003) 73–78We report the kinetic behavior of the enzyme aldehyde oxidoreductase (AOR) from the sulfate reducing bacterium Desulfovibrio
gigas (Dg) encapsulated in reverse micelles of sodium bis-(2-ethylhexyl) sulfosuccinate in isooctane using benzaldehyde, octaldehyde,
and decylaldehyde as substrates. Dg AOR is a 200-kDa homodimeric protein that catalyzes the conversion of aldehydes to carboxylic
acids. Ultrasedimentation analysis of Dg AOR-containing micelles showed the presence of 100-kDa molecular weight species, confirming that the Dg AOR subunits can be dissociated. UV–visible spectra of encapsulated Dg AOR are indistinguishable
from the enzyme spectrum in solution, suggesting that both protein fold and metal cofactor are kept intact upon encapsulation. The catalytic constant (kcat) profile as a function of the micelle size W0 (W0 ¼ ½H2O /[AOT]) using benzaldehyde as substrate showed two bell-shaped activity peaks at W0 ¼ 20 and 26. Furthermore, enzymatic activity for octaldehyde and decylaldehyde was detected only in reverse micelles. Like for the benzaldehyde kinetics, two peaks with both similar kcat values and W0 positions were obtained. EPR studies using spin-labeled reverse micelles indicated that octaldehyde and benzaldehyde are intercalated in the micelle membrane.
This suggests that, though Dg AOR is found in the cytoplasm of bacterial cells, the enzyme may catalyze the reaction of substrates incorporated into a cell membrane
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