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Tytuł:
Intranasal (IN) COVID-19 vaccines - a breakthrough
Autorzy:
Gambhir, R.S.
Kaur, K.
Matariya, R.
Singh, B.
Sood, R.
Singh, J.
Powiązania:
https://bibliotekanauki.pl/articles/28765534.pdf
Data publikacji:
2023
Wydawca:
Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
Opis:
Emerging variants of COVID-19 have threatened the effectiveness of intramuscular (IM) vaccines since that are made to target only the spike protein. Development of Intranasal (IN) vaccination has been proven to provide both the mucosal and systemic immune responses for broader and long lasting protection. Many IN vaccine candidates (virus-vectored vaccines, recombinant subunit vaccines and live attenuated vaccines) are in different phases of clinical trials and in near future many companies would be releasing their vaccines into the drug market. Potential advantages of IN vaccination over IM vaccination makes them ideal to be administered in children and developing populations of the world. This paper focuses on the very recent developments in intranasal vaccination with a spotlight on their safety and efficacy concerns. IN vaccination can prove to be game-changer in handling COVID-19 and potential viral contagious diseases in future.
Źródło:
Roczniki Państwowego Zakładu Higieny; 2023, 74, 1; 15-18
0035-7715
Pojawia się w:
Roczniki Państwowego Zakładu Higieny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Covid-19 update: Omicron variant − a new emerging threat
Autorzy:
Mehta, S.
Gambhir, R.S.
Singh, B.
Goel, R.
Ghuman, K.S.
Aggarwal, A.
Powiązania:
https://bibliotekanauki.pl/articles/2083083.pdf
Data publikacji:
2022
Wydawca:
Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
Tematy:
COVID-19
SARS-CoV-2 pandemic
Omicron variant
vaccine
coronavirus pandemic
Opis:
A new health threat in the form of a new variant of Covid-19 called Omicron has emerged globally in this holiday season. This new variant has been declared a variant of concern (VOC) by the World Health Organization and experts are expecting another wave of the pandemic. A lot still unknown about this variant and researchers worldwide are conducting studies to find the nature and characteristics of this mutated strain. Cases have begun to rise dramatically around the world and many countries have already imposed travel restrictions again to prevent disease transmission. It is being speculated that this particular variant has got tendency of immune escape and therefore can even infect fully vaccinated individuals. Vaccination and adhering to Covid-19 guidelines and protocols can curtail the spread of the virus. The present paper focuses on what is currently known about this variant, antigen diagnostic tests, importance of getting fully vaccinated and having booster dose etc. If we want to emerge from this pandemic, countries should practice vaccine equality and solidarity for the good of mankind.
Źródło:
Roczniki Państwowego Zakładu Higieny; 2022, 73, 1; 13-16
0035-7715
Pojawia się w:
Roczniki Państwowego Zakładu Higieny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Passerine birds supporting cross pollination in Erythrina stricta Roxb.
Autorzy:
Khanduri, V.P.
Kumar, K.S.
Sharma, C.M.
Riyal, M.K.
Kar, K.
Singh, B.
Sukumaran, A.
Powiązania:
https://bibliotekanauki.pl/articles/2078260.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
Ornithophily
pollination
mating system
geitonogamy
pollen grains
Opis:
Erythina stricta is an ecologically important tree species in the rainforests of India and its nectar within the flowers contributes to birds’ diet and survival. Reports on the pollination of this species have not been published so far. We therefore explore the reproductive system of this tree species which has great significance to its ecosystem. Birds have an important role in the reproduction of trees through pollination particularly in tropical areas where reproductive success mostly depends on animal pollinator interactions. Study of visitation and nectar feeding behaviour of birds alongwith breeding system assessment of Erythina stricta. Birds visiting and foraging behaviour was observed during Erythrina stricta flowering season in an indian tropical rainforest. Reproductive system was assessed through controlled pollination experiments. Thirteen bird species were recorded visiting and foraging nectar from the flowers of Erythrina stricta. The maximum numbers of visits recorded were from the Red-vented Bulbul (Pycnonotus cafer, Pycnonotidae). The nectar feeding birds were, either (i) potential pollinator with long bills (e.g. Pycnonotus spp., Chloropsis aurifrons, and Dicrurus spp.) or (ii) nectar robbers with comparatively shorter bills (e.g. Zosterops palpebrosa, Stachyris ruficeps, Macronous gularis, Heterophasia glaciris). Controlled pollination experiments revealed high degree of cross pollination (xenogamy) and self-incompatibility in E. stricta. Birds were more frequent in early mornings and their foraging activity was also observed during evening hours; the frequency however, declined with respect to nectar availability. Long corolla tubes of E. stricta could restrict access to nectar collecting bees
Źródło:
Dendrobiology; 2021, 85; 117-126
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chaotic convection of viscoelastic fluid in porous medium under G-jitter
Autorzy:
Bhadauria, B. S.
Singh, A.
Singh, M. K.
Powiązania:
https://bibliotekanauki.pl/articles/265559.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
teoria nieliniowa
grawitacja
konwekcja
non-linear theory
gravity modulation
chaotic convection
Opis:
The present article aims at investigating the effect of gravity modulation on chaotic convection of a viscoelastic fluid in porous media. For this, the problem is reduced into Lorenz system (non-autonomous) by employing the truncated Galerkin expansion method. The system shows transitions from periodic to chaotic behavior on increasing the scaled Rayleigh number R. The amplitude of modulation advances the chaotic nature in the system while the frequency of modulation has a tendency to delay the chaotic behavior which is in good agreement with the results due to [1]. The behavior of the scaled relaxation and retardation parameter on the system is also studied. The phase portrait and time domain diagrams of the Lorenz system for suitable parameter values have been used to analyze the system.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 1; 37-51
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Closure of municipal solid waste dumps. Site rating for odor impact
Autorzy:
Kumar, A.
Datta, M.
Nema, A. K.
Singh, R. K.
Gurjar, B. R.
Powiązania:
https://bibliotekanauki.pl/articles/208306.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
population statistics
waste dumps
odour nuisance
statystyki ludności
składowiska odpadów
uciążliwość zapachowa
Opis:
More than 60% of the waste dumps in India are within 500 m from the communities. The odor impact from these sites may be the sole criterion to prioritize these sites for closure/remediation. The existing rating systems do not consider odor impact in their assessment. A new system, proposed in the study, employs seven parameters derived from the literature review and selects their ratings based on data obtained from a survey of waste dumps in Indian cities having population more than one million and expert judgment. Application of the new system to the waste sites with continuously varying characteristics shows that the scores are spread over the full range of 0–1000 and have minimum clustering. The sensitivity analysis of the new system shows that the system exhibits medium to high sensitivity to five out of seven parameters employed in the system. The odor impact ratings for the fifteen waste dumps from the new system prioritize these dumps into three categories for remedial action and help suggesting a particular cover alternative for these dumps.
Źródło:
Environment Protection Engineering; 2018, 44, 2; 37-56
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural convection in a hydrodynamically and thermally anisotropic non-rectangular porous cavity: effect of internal heat generation/absorption
Autorzy:
Chandran, P.
Sacheti, N. C.
Bhadauria, B. S.
Singh, A. K.
Powiązania:
https://bibliotekanauki.pl/articles/264468.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja naturalna
materiały porowate
przepuszczalność
dyfuzyjność cieplna
źródło ciepła
natural convection
trapezoidal cavity
porous medium
permeability
thermal diffusivity
Darcy's law
heat source/sink
Opis:
Laminar natural convection in a trapezoidal porous vertical cavity has been investigated in this work. It is assumed that the porous enclosure is filled up with a permeable material subject to hydrodynamic and thermal anisotropy, the flow being governed by the Darcy law as applicable to a non-isotropic medium. It is further assumed that (i) there is heating at the left vertical wall and cooling at the right wall of the enclosure and (ii) the flow domain is subject to the presence of heat source or heat sink. The partial differential equations governing the resulting free convection have been solved numerically in the non-dimensional forms. There arises a number of parameters relating to buoyancy, internal heating, cavity aspect ratio and inclination of the upper surface to the horizontal. The influence of these parameters has been illustrated and analyzed through contours of streamlines and isotherms. We have also discussed the role of internal heating as well as anisotropy on the heat transfer characteristics.
Źródło:
International Journal of Applied Mechanics and Engineering; 2018, 23, 3; 595-609
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence Properties of CaAl₂O₄:Eu³⁺, Gd³⁺ Phosphors Synthesized by Combustion Synthesis Method
Autorzy:
Verma, N.
Singh, K.
Marí, B.
Mollar, M.
Jindal, J.
Powiązania:
https://bibliotekanauki.pl/articles/1030093.pdf
Data publikacji:
2017-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
phosphors
luminescence
combustion method
calcium aluminate
Opis:
CaAl₂O₄:Eu³⁺ (1 mol.%) co-doped with varying concentration of Gd³⁺ (1, 2, 5, and 10 mol.%) were prepared by combustion synthesis method at 600°C and further annealed at 1000°C. All the compositions were investigated for their structural and photoluminescence properties. It was observed that both states of europium i.e. Eu³⁺ and Eu²⁺ were present and ratio of these states changes on heating at 1000°C. The materials synthesized at 600°C showed high intense peak around 440 nm due to presence of Eu²⁺ and less intense peaks in the red region which were due to presence of Eu³⁺. On annealing the compounds at 1000°C, intensity of peak around 440 nm decreases and intensity of peaks in the red region increases significantly. The ⁵D₀ → ⁷F₃ transition due to Eu³⁺ at 657 nm appears as the highest intensity peak. All co-doped samples annealed at 1000°C showed the higher intensity than the mono doped sample which is due to energy transfer from the Gd³⁺ to Eu³⁺. The second rare-earth ion (Gd³⁺) acts as sensitizer and enhances the photoluminescence intensity. The X-ray diffraction spectra reveal the monoclinic phase of CaAl₂O₄ in all the samples which showed that Eu³⁺ and Gd³⁺ do not change the crystalline structure of calcium aluminate.
Źródło:
Acta Physica Polonica A; 2017, 132, 4; 1261-1264
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anodic oxide films on niobium and tantalum in different aqueous electrolytes and their impedance characteristics
Autorzy:
Verma, N.
Singh, K.
Marí, B.
Mollar, M.
Jindal, J.
Powiązania:
https://bibliotekanauki.pl/articles/1075354.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.37.Hk
68.55.J-
68.60.Bs
Opis:
The anodic oxide films were prepared on the niobium and tantalum in aqueous electrolyte mixtures containing 1 M CH₃COOH + 1 M H₃PO₄ or 1 M CH₃COOH + 1 vol.% HF or 1 M CH₃COOH + 1 M H₃PO₄ + 1 vol.% HF at 30 V for 30 min. The barrier films were obtained on both niobium and tantalum surfaces in all electrolyte mixtures except niobium oxide film formed in 1 M CH₃COOH + 1 vol.% HF which is porous in nature. The anodic oxide films were characterized by FESEM. Also, electrochemical impedance spectroscopy at open-circuit potential on Nb and Ta was applied and obtained data were analyzed by fitting with four different equivalent circuits.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 297-303
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of flux composition on the percentage elongation and tensile strength of welds in submerged arc welding
Efekt składu topnika na wydłużenie procentowe i wytrzymałość na rozciąganie spawów przy spawaniu łukiem krytym
Autorzy:
Singh, B.
Khan, Z. A.
Siddiquee, A. N.
Maheswari, S.
Sharma, S. K.
Powiązania:
https://bibliotekanauki.pl/articles/140322.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ultimate tensile strength
carbon equivalent
basicity index
elements transfer
delta quantity
UTS
wytrzymałość na rozciąganie
równoważnik węglowy
współczynnik zasadowości
transfer pierwiastków
wielkość delta
Opis:
This experimental study reveals the effects of CaF2, FeMn and NiO additions to the base fluxes on tensile strength and percentage elongation of the weld metal. The aim of this study is to develop suitable flux for mild steel for high tensile strength, impact strength and ductility. Bead on plate welds were made using submerged arc welding process. Mathematical model for percentage elongation and UTS of mild steel welds were made. The elements transfer to the welds have been correlated with the above mechanical performance characteristics. The effect of oxygen content on weld elongation and UTS also has been deduced. This study shows that CaF2 and NiO are the significant factors for tensile strength while FeMn is not significant for tensile strength. However, for elongation besides CaF2, the interaction of CaF2 and FeMn was also found significant. The effects of basicity index of the flux and carbon equivalent of the welds on tensile strength and percentage elongation of the welds have also been evaluated.
W studium eksperymentalnym, przedstawionym w pracy, pokazano wpływ domieszek CaF2, FeMn i NiO do podstawowego składu topnika na wytrzymałość na rozciąganie i procentowe wydłużenie metalu spawu. Celem studium było opracowanie topnika odpowiedniego dla stali niskowęglowej, który zapewnia wysoką wytrzymałość na rozciąganie, wytrzymałość na udary i plastyczność. Ściegi spawów wykonano metodą spawania łukiem krytym. Opracowano model matematyczny wydłużenia procentowego i wytrzymałości na rozciąganie (UTS) dla spawów ze stali niskowęglowej. Zbadano korelację między wymienionymi charakterystykami mechanicznymi a transferem pierwiastków do spawu. Wyznaczono także wpływ zawartości tlenu na wydłużenie spawu i ostateczną wytrzymałość na rozciąganie. W badaniach doświadczalnych wykazano, że domieszki CaF2 oraz NiO są istotnymi czynnikami wpływającymi na wytrzymałość na rozciąganie, podczas gdy domieszka FeMn nie ma istotnego wpływu. Oceniono także wpływ współczynnika zasadowości topnika i równoważnika węglowego spawu na wydłużenie procentowe spawu.
Źródło:
Archive of Mechanical Engineering; 2016, LXIII, 3; 337-354
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Studies on Advanced Sheet Explosive Formulations Based on 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and Hydroxyl Terminated Polybutadiene (HTPB), and Comparison with a RDX-based System
Autorzy:
Jangid, S. K.
Talawar, M. B.
Singh, M. K.
Nath, T.
Sinha, R. K.
Powiązania:
https://bibliotekanauki.pl/articles/358055.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
hazardous materials
sheet explosive
explosive reactive armour (ERA)
CL-20
RDX
Opis:
The present investigation reports the use of 2,4,6,8,10,12-hexanitro2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) in sheet explosive formulations. In this study, hydroxyl terminated polybutadiene (HTPB) based sheet explosives were prepared incorporating the powerful explosive CL-20 as a partial replacement for hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX). The effects of incorporating CL-20 on the performance, sensitivity, thermal and mechanical properties of the sheet explosive compositions are reported. Sheet explosive formulation containing 80% of RDX and 20% of HTPB-binder was studied as control sample. HTPBbinder consisted of 12% HTPB, 2.9% dioctyl adipate (DOA) and 5.1% dioctyl phthalate (DOP). HTPB was cured with 4,4’-methylene diphenyl di-isocyanate (MDI) to form urethane linkages. The incorporation of 20% of CL-20 in place of RDX led to a remarkable increase in the velocity of detonation (VOD), of the order of 7680 m/s, and to better mechanical properties in terms of tensile strength (1.14 MPa) compared to the control formulation [RDX /HTPB-binder (80/20)]. The 20% CL-20 incorporated sheet explosive formulation also showed remarkable increases in impact and shock sensitivity. Thermal analysis of the sheet explosive compositions has also been carried out using differential scanning calorimetry (DSC).
Źródło:
Central European Journal of Energetic Materials; 2016, 13, 1; 135-147
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability analysis and internal heating effect on oscillatory convection in a viscoelastic fluid saturated porous medium under gravity modulation
Autorzy:
Bhadauria, B. S.
Singh, M. K.
Singh, A.
Singh, B. K.
Kiran, P.
Powiązania:
https://bibliotekanauki.pl/articles/265014.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
analiza stabilności
grawitacja
ciecz lepkosprężysta
nonlinear stability analysis
complex Ginzburg-Landau equation
gravity modulation
internal heating
bifurcation
Opis:
In this paper, we investigate the combined effect of internal heating and time periodic gravity modulation in a viscoelastic fluid saturated porous medium by reducing the problem into a complex non-autonomous Ginzgburg-Landau equation. Weak nonlinear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number is obtained in terms of the amplitude for oscillatory mode of convection. The influence of viscoelastic parameters on heat transfer has been discussed. Gravity modulation is found to have a destabilizing effect at low frequencies and a stabilizing effect at high frequencies. Finally, it is found that overstability advances the onset of convection, more with internal heating. The conditions for which the complex Ginzgburg-Landau equation undergoes Hopf bifurcation and the amplitude equation undergoes supercritical pitchfork bifurcation are studied.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 4; 785-803
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oscillatory MHD convective flow of second order fluid through porous medium in a vertical rotating channel in slip-flow regime with heat radiation
Autorzy:
Garg, B. P.
Singh, K. D.
Bansal, A. K.
Powiązania:
https://bibliotekanauki.pl/articles/264392.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
slip flow
convective
porous medium
rotating
oscillatory
radiation
second order fluid
porowatość
promieniowanie
magnetohydrodynamika
Opis:
An analysis of an oscillatory magnetohydrodynamic (MHD) convective flow of a second order (viscoelastic), incompressible, and electrically conducting fluid through a porous medium bounded by two infinite vertical parallel porous plates is presented. The two porous plates with slip-flow condition and the no-slip condition are subjected respectively to a constant injection and suction velocity. The pressure gradient in the channel varies periodically with time. A magnetic field of uniform strength is applied in the direction perpendicular to the planes of the plates. The induced magnetic field is neglected due to the assumption of a small magnetic Reynolds number. The temperature of the plate with no-slip condition is non-uniform and oscillates periodically with time and the temperature difference of the two plates is assumed high enough to induce heat radiation. The entire system rotates in unison about the axis perpendicular to the planes of the plates. Adopting complex variable notations, a closed form solution of the problem is obtained. The analytical results are evaluated numerically and then presented graphically to discuss in detail the effects of different parameters of the problem. The velocity, temperature and the skin-friction in terms of its amplitude and phase angle have been shown graphically to observe the effects of the viscoelastic parameter γ, rotation parameter Ω, suction parameter […], Grashof number Gr, Hartmann number M, the pressure A, Prandtl number Pr, radiation parameter N and the frequency of oscillation […].
Źródło:
International Journal of Applied Mechanics and Engineering; 2015, 20, 1; 33-52
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of temperature of black holes in terms of Chandrasekhar limit
Autorzy:
Mahto, D.
Jha, B. K.
Singh, K.M.
Ram, M.
Powiązania:
https://bibliotekanauki.pl/articles/412044.pdf
Data publikacji:
2015
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
black holes
formula for the temperature
Hawking
Einstein
Opis:
Stephen Hawking gave the formula for the temperature for the black holes as[wzór] . In the present research article, we have converted this formula in terms of Chandrasekhar limit [Mch] and also calculated their values for different test black holes existing in XRBs and AGN. [wzór] Kelvin.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2015, 40; 43-50
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of organic inputs on strength and stability of soil aggregates under rice-wheat rotation
Autorzy:
Das, B.
Chakraborty, D.
Singh, V.K.
Aggarwal, P.
Singh, R.
Dwivedi, B.S.
Powiązania:
https://bibliotekanauki.pl/articles/25472.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
tensile strength
stability
soil aggregate
rice
wheat
cereal crop rotation
Opis:
The study aims to elucidate the impact of organic inputs on strength and structural stability of aggregates in a sandy loam soil. Tensile strength, friability and water stability of aggregates, and the carbon contents in bulk soil and in large macro (>2 mm), small macro (0.25-2 mm), micro (0.053-0.25 mm) and silt+clay size (<0.053) aggregates were evaluated in soils from a long-term experiment with rice-wheat rotation at Modipuram, India, with different sources and amounts of organic C inputs as partial substitution of N fertilizer. Addition of organic substrates significantly improved soil organic C contents, but the type and source of inputs had different impacts. Tensile strength of aggregates decreased and friability increased through organic inputs, with a maximum effect under green gram residue (rice)-farmyard manure (wheat) substitution. Higher macroaggregates in the crop residue- and farmyard manure-treated soils resulted in a higher aggregate mean weight diameter, which also had higher soil organic C contents. The bulk soil organic C had a strong relation with the mean weight diameter of aggregates, but the soil organic C content in all aggregate fractions was not necessarily effective for aggregate stability. The soil organic C content in large macroaggregates (2-8 mm) had a significant positive effect on aggregate stability, although a reverse effect was observed for aggregates <0.25 mm. Partial substitution of nitrogen by organic substrates improved aggregate properties and the soil organic C content in bulk soil and aggregate fractions, although the relative effect varied with the source and amount of the organic inputs.
Źródło:
International Agrophysics; 2014, 28, 2
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of Ammonium Sulfamate Nitration for the Preparation of Ammonium Dinitramide
Autorzy:
Mandal, A. K.
Kunjir, G. M.
Singh, J.
Adhav, S. S.
Singh, S. K.
Pandey, R. K.
Bhattacharya, B.
Lakshmi Kantam, M.
Powiązania:
https://bibliotekanauki.pl/articles/358022.pdf
Data publikacji:
2014
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Opis:
The reaction kinetics for the preparation of ammonium dinitramide (ADN) is described. ADN is the ammonium salt of the dinitramide anion, and belongs to the group of inorganic oxidizers, mainly useful for energetic rocket propellant formulations, particularly for underwater applications. It is also a potential candidate to replace ammonium perchlorate (AP), in order to develop chlorine-free, green propellants. At HEMRL, ADN is prepared by the nitration of ammonium sulfamate (AS) using mixed acid, followed by hydrolysis, neutralization with ammonia (g) and rectification using solvent. The nitration of ammonium sulfamate (AS) is carried out at a subzero temperature of -40 ±1 °C. The yield of ADN is reliant on the formation of dinitramidic acid, an intermediate product formed during the hydrolysis step, and its stability is predominantly dependent upon the level of acidity and temperature of the reaction medium. Prior to these kinetics studies, process optimization of the nitration of ammonium sulfamate (AS) was performed and gave the final mole ratio of AS:HNO3:H2SO4. Since the nitration of AS is sensitive to temperature, the rate of reaction was studied at fixed temperatures with variation of time, keeping all of the other parameters, such as vessel volume, agitator speed, feed rate etc., constant. During these studies, predetermined quantities of ammonium sulfamate (AS) and mixed acid were allowed to react at a fixed temperature (-40 ±1 °C) for different reaction periods to generate the concentration profile of AS. Using this concentration profile, the reaction order and reaction rate constant were evaluated. In order to find the effect of temperature on the reaction rate and yield, experiments were conducted at other temperatures such as -30 and -50 °C. In the present studies, it was found that the optimum temperature of nitration is -40 ±1 °C and that the rate of reaction follows a pseudo second order process with rate constant 0.01113 (min-1)•(mol/L)-1. The reaction time evaluated for 55 to 60% conversion is about 70-80 minutes at -40 ±1 °C, based on this kinetics. The activation energy of AS nitration was found to be -4.6 kcal/mol, using the reaction kinetic data based on the temperature dependent rate equation derived from Arrhenius’s law.
Źródło:
Central European Journal of Energetic Materials; 2014, 11, 1; 83-97
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 27

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