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    Wyświetlanie 1-13 z 13
    Tytuł:
    Indian Ocean wind speed variability and global teleconnection patterns
    Autorzy:
    Sinha, M.
    Jha, S.
    Chakraborty, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/2079299.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Oceanologii PAN
    Tematy:
    wind speed
    variability
    sea surface temperature
    remote sensing
    Indian Ocean
    Opis:
    The influence of the local sea surface temperature (SST) and remote ENSO (El Niño-Southern Oscillation) indices on the wind speed (WS) data were explored for the Indian Ocean region. Relationships among the parameters were studied using spatial correlation plots and significant correlation ranges. Two months (July and January) representing opposite monsoon phases were selected for analysis for the period 1950–2016. There was a significant negative correlation between WS and SST over the Bay of Bengal (BOB) during July. Although different ENSO indices correlated differently in different areas of the Indian Ocean, the region off the coast of Sri Lanka was most significantly teleconnected. The southwest monsoon locally impacted the WS and SST relationship and the WS parameter was remotely teleconnected in both the monsoon seasons. Further empirical orthogonal function (EOF) analysis was applied on the 67 years WS data of the BOB region to extract the dominant mode representing maximum variability of the total variance. The temporal pattern of the first principal component (PC1) of WS data was linked to the North Atlantic Oscillations in January and the Atlantic Multidecadal Oscillation in July respectively. The continuous wavelet power spectra of the PC1 of WS showed significant regions in the 2–4-year band resembling the ENSO variability. Wavelet coherence applied between PC1 of WS and the ENSO indices showed greatest values for January in the 8–16-year band and for July in the 0–4-year band. A close relationship was established between the WS variability in BOB and the ENSO indices.
    Źródło:
    Oceanologia; 2020, 62, 2; 126-138
    0078-3234
    Pojawia się w:
    Oceanologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of antioxidant potential of pigments extracted from Bacillus spp. and Halomonas spp. isolated from mangrove rhizosphere
    Autorzy:
    Patkar, S.
    Shinde, Y.
    Chindarkar, P.
    Chakraborty, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/2096392.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    biopigment
    antioxidant
    SPF
    rhizosphere soil
    Opis:
    The present study aimed to isolate different pigment-producing bacteria from the mangrove rhizosphere habitat and to extract their pigments for evaluating their antioxidant and sun-protective properties. Three pigment-producing bacterial cultures were isolated from soil samples and were identified by morphological analysis and 16S rDNA sequencing. The pigments were isolated by the solvent extraction method and named as MZ (Pink), Orange, and Yellow. They were characterized by Fourier Transform Infrared (FTIR) and UV-Vis spectroscopy. The sun protection factor (SPF) values of these pigments were then determined using the Mansur equation. The total polyphenol content was estimated by the Folin-Ciocâlteu method, and the antioxidant activity of the pigments was determined using DPPH (2,2-diphenyl-1-picrylhydrazyl), FRAP (ferric reducing antioxidant power), and ABTS (2,2-azinobis-3-ethyl-enzothiazoline-6-sulfonic acid) assays. The in vitro antioxidant potential of the pigments in the presence of oxidative stress (H2O2) was confirmed in the mouse macrophage cell line RAW264.7 by using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The pigment-producing bacterial isolates were identified as Bacillus infantis (MZ), Halomonas spp. (Orange), and Bacillus spp. (Yellow). The pigments were found to be carotenoid in nature, and the SPF values were in the range of 3.99 to 5.22. All three pigments had high polyphenol content (22 to 48 μg tannic acid equivalent) and showed significant antioxidant properties in both chemical and cell line-based studies. The results of this study indicate that these pigments have the potential to be used as an antioxidant agent and can be further developed as a pharmaceutical compound.
    Źródło:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2021, 102, 2; 157-169
    0860-7796
    Pojawia się w:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal selection of dental implant for different bone conditions based on the mechanical response
    Autorzy:
    Roy, S.
    Das, M.
    Chakraborty, P.
    Biswas, J. K.
    Chatterjee, S.
    Khutia, N.
    Saha, S.
    Roychowdhury, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/307549.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    wytrzymałość kości
    implanty stomatologiczne
    analiza FEM
    pacjent
    bone condition
    porous dental implant
    FE Analysis
    patient specific
    Opis:
    Bone quality varies from one patient to another extensively; also, Young’s modulus may deviate up to 40% of normal bone quality, which results into alteration of bone stiffness immensely. The prime goal of this study is to design the optimum dental implant considering the mechanical response at bone implant interfaces for a patient with specific bone quality. Method. 3D model of mandible and natural molar tooth were prepared from CT scan data while, dental implants were modelled using different diameter, length and porosity and FE analysis was carried out. Based on the variation in bone density, five different bone qualities were considered. First, failure analysis of implants, under maximum biting force of 250N had been performed; next, the implants, those survived were selected for observing the mechanical response at bone implant interfaces under common chewing load of 120N. Result. Maximum Von Mises stress did not surpass the yield strength of the implant material (TiAl4V). However, factor of safety of 1.5 was considered and all but two dental implants survived the design stress or allowable stress. Under 120N load, distribution of Von Mises stress and strain at the bone-implant interface corresponding to the rest of the implants for five bone conditions were obtained and enlisted. Conclusion. Implants, exhibiting interface strain within 1500-3000 microstrain range show the best bone remodelling and osseointegration. So, implant models, having this range of interface strains were selected corresponding to the particular bone quality. A set of optimum dental implants for each of the bone qualities were predicted.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2017, 19, 2; 11-20
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimization of Jigging Process Parameters to Beneficiate Iron Ore Fines – a Case Study of Tatasteel
    Optymalizacja parametrów procesu wzbogacania w osadzarce drobnouziarnionej rudy żelaza – studium przypadku Tatasteel
    Autorzy:
    Shukla, Vishal
    Kumar, C. Raghu
    Chakraborty, D. P.
    Kumar, Ashok
    Powiązania:
    https://bibliotekanauki.pl/articles/318528.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Przeróbki Kopalin
    Tematy:
    osadzarka
    granulometria
    jakość nadawy
    wysokość łoża osadzarki
    wydajność
    wydajność separacji
    wzbogacanie żelaza
    jigging
    granulometry
    feed quality
    bed height
    yield
    separation efficiency
    iron separation
    Opis:
    Jigging has a very important role in mineral processing Industry. Upgrading of Iron Ore by jigging has been an emerging trend. A detailed investigation is carried out to understand the role of jig feed distribution and process parameters during jigging operation. Noamundi jig plant data shows that variation in jig feed granulometry, feed quality and operating conditions are major contributors to fluctuation in jigging performance. At Noamundi the Jig feed size (-10.0+0.5mm) fraction is used for fines jigging operation. To understand the effect of particle size distribution on jig plant performance such as yield, separation efficiency and Fe recovery. In this context The performance of jigging was evaluated by daily average data from jig operation was used to study the influence of feed distribution on jigging performance .Coarser fraction (+6mm) has a positive influence, whereas fines fraction (-0.5mm) tends to lower performance .During Jigging rearrangements of Particles takes place due to an alternate expansion and compaction of Jig Bed .These particles are arranged by increasing density from top to bottom. During the particle stratification, Jig bed physically cut at desired horizontal particle density plant to separate the desired product. Investigation shows that optimum bed height is required at different Jig feed quality to achieve desired product quality, maximum separation efficiency and Fe recovery. This Paper will illustrate role of feed distribution and process parameters control on Jigging plant performance and deals with optimization of process parameters to recover iron value from fines.
    Wzbogacanie w osadzarce odgrywa bardzo ważną rolę w przemyśle przetwórstwa minerałów. Wzbogacanie rudy żelaza w osadzarkach jest nowym kierunkiem badań nad wzbogacalnością. Przeprowadzono szczegółowe badania w celu określenia wpływu uziarnienia nadawy i parametrów procesu na efektywność procesu. Dane dotyczące wzbogacania w zakładzie Noamundi pokazują, że zróżnicowanie składu ziarnowego nadawy i warunki procesu są głównymi czynnikami wpływającymi na wahania wydajności osadzarki. W Zakładzie Noamundi do wzbogacania w osadzarce kierowana jest klasa ziarnowa (10,0–0,5 mm). Zbadano wpływ rozkładu wielkości cząstek na wydajność osadzarki, taką jak wydajność, skuteczność rozdziału i odzysk żelaza. Wydajność osadzarki oceniono na podstawie średnich dziennych danych z osadzarki przemysłowej, które wykorzystano do zbadania wpływu parametrów nadawy na wydajność. Udział grubszych ziaren (+6 mm) ma pozytywny wpływ, podczas gdy drobnych ziaren (-0,5 mm) ma tendencję do obniżania wydajności. W procesie osadzania następują zmiany gęstości łoża. Zmiana gęstości łoża następuje od góry (najniższa) do dołu (największa). Podczas stratyfikacji ziaren warstwa materiału jest rozdzielana na określonym poziomie, tak aby uzyskać produkt o pożądanej charakterystyce. Badanie wykazało, że optymalna wysokość łoża osadzarki jest różna dla różnej charakterystyki nadawy tak aby osiągnąć pożądaną jakość produktu, maksymalną wydajność separacji i odzysk Fe. W niniejszym artykule zilustrowano rolę jakości nadawy i kontroli parametrów procesu dla uzyskania wydajności osadzarki, oraz przedstawiono optymalizację parametrów procesu w celu maksymalizacji uzysku żelaza.
    Źródło:
    Inżynieria Mineralna; 2019, 21, 1/2; 165-170
    1640-4920
    Pojawia się w:
    Inżynieria Mineralna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact of Flotation Machine Characteristics on the Performance of Fine Coal Beneficiation (-0.5mm & -0.25mm) – a Case Study of Tatasteel
    Wpływ doboru maszyny flotacyjnej na wyniki wzbogacalności drobnego węgla (-0,5 mm i -0,25 mm) – studium przypadku Tatasteel
    Autorzy:
    Dhavala, Bhargav
    Koparthi, Prasad
    Singh, Jitender
    Sit, Suman Krishna
    Chakraborty, D. P.
    Powiązania:
    https://bibliotekanauki.pl/articles/318961.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Przeróbki Kopalin
    Tematy:
    maszyny flotacyjne mechaniczne
    maszyny flotacyjne kolumnowe
    maszyny flotacyjne Jamesona
    uzysk
    mechanical cells
    column cells
    jameson cells
    unit yield
    Opis:
    Tatasteel coal washeries at West Bokaro are designed to treat (+) 0.5mm in dense media cyclones & (-) 0.5mm in mechanical type flotation cells. Typically, ~20% of the raw coal feed reports to the flotation circuit. Through several plant audits carried out for the fines circuit, it was established that there is a scope for yield improvement in the fines circuit by ~3–4% on raw coal basis w.r.t the maximum theoretical flotability of the coal. Flotation is a complex process controlled by factors which can be divided into three facets: coal characteristics, chemistry and machine characteristics. Factors within the coal and chemistry areas are dynamic and hence, need to be dealt with by personnel on an ongoing basis in normal plant operations. One of the most important characteristics of any flotation technology is air bubble generation and the size of air bubbles produced as this controls flotation kinetics and also, it dictates the carrying capacity of the machine. Another crucial component is how the machine effects collision and contact between air bubbles and particles. Apart from mechanical type flotation cells, the most popular flotation technologies elsewhere are Jameson & Column flotation. Jameson cells hold an edge over Column & mechanical flotation cells in terms of providing better kinetics, low footprint, lower operating & maintenance costs. In the present study, authors have tested West Bokaro coal in conventional mechanical & Column flotation cells at Tatasteel R&D whereas testwork in Jameson flotation cells was carried out at University of Queensland (Australia) for (-)0.5mm & (-)0.25mm size fractions .Results for (-)0.5mm size fraction show that Jameson cell gives 78.5% yield , Column cells give ~71% compared to 65% in mechanical cells on unit basis. Results for (-)0.25mm size fraction show that Jameson cell gives 87% yield , Column cells give ~83% compared to 80% in mechanical cells on unit basis. It is evident from the testwork carried out that Jameson cells are capable of giving higher yields at the same product ash and based on the same ,a pilot scale installation of Jameson cells has been proposed to validate the lab findings.
    Zakłady wzbogacania Tatasteel w West Bokaro są przeznaczone do przeróbki klasy ziarnowej +0,5 mm w cyklonach z cieczą ciężką i klasy ziarnowej -0,5 mm w mechanicznych maszynach flotacyjnych. Zazwyczaj ~20% surowego węgla podaje się do flotacji. W wyniku szeregu badań układu wzbogacania miału węglowego ustalono, że istnieje możliwość poprawy wydajności wzbogacania miału o ~3–4% w przeliczeniu na surowy węgiel. Flotacja jest złożonym procesem który zależy od szeregu czynników , które można podzielić na trzy grupy: charakterystykę węgla, zjawiska fizykochemiczne i charakterystykę maszyny. Czynniki w obszarze są dynamiczne i dlatego obsługa procesu musi na bieżąco je kontrolować podczas normalnej pracy zakładu. Jedną z najważniejszych cech technologii flotacji jest generowanie pęcherzyków powietrza i wielkość wytwarzanych pęcherzyków powietrza, ponieważ wpływa to na kinetykę flotacji, a także decyduje o wydajności maszyny. Kolejnym istotnym elementem jest wpływ kontaktu pęcherzyków powietrza z cząsteczkami w maszynie flotacyjnej. Oprócz mechanicznych komór flotacyjnych, najpopularniejszymi technologiami flotacji są maszyny flotacyjne Jamesona i kolumnowe. Maszyny flotacyjne Jamesona mają przewagę nad kolumnowymi i mechanicznymi komorami flotacyjnymi pod względem lepszej kinetyki flotacji, małych gabarytów, niższych kosztów eksploatacji i konserwacji. W niniejszym artykule autorzy pokazali wyniki flotacji węgla West Bokaro w konwencjonalnych mechanicznych i kolumnowych maszynach flotacyjnych w Tatasteel R&D. Badania w komorach flotacyjnych Jamesona przeprowadzono na University of Queensland (Australia) dla węgla o uziarnieniu - 0,5 mm i - 0,25 mm. Wyniki dla klasy ziarnowej o wielkości -0,5 mm pokazują, że w komorze Jamesona uzysk wynosi 78,5%, w maszynie kolumnowej ~71% w porównaniu do 65% w maszynie mechanicznej. Wyniki dla klasy ziarnowej - 0,25 mm pokazują, że w komorach Jamesona otrzymuje się uzysk 87%, w maszynie kolumnowej ~83% w porównaniu do 80% w maszynie mechanicznej. Z przeprowadzonych testów wynika, że maszyny Jamesona są w stanie dawać wyższe wydajności przy tej samej zawartości popiołu w produkcie. Na tej samej podstawie zaproponowano instalację maszyn flotacyjnych Jamesona w skali pilotażowej w celu potwierdzenia wyników badań laboratoryjnych.
    Źródło:
    Inżynieria Mineralna; 2019, 21, 1/2; 113-116
    1640-4920
    Pojawia się w:
    Inżynieria Mineralna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Critical swim speed and metabolic activities in trained male and female swimmers after 400 m free style swimming with their full effort
    Autorzy:
    Chatterjee, P.
    Nandy, P.
    Chakraborty, S.
    Bandyopadhyay, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1918384.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Medyczny w Białymstoku
    Tematy:
    Critical swim speed
    creatinine
    young s wimmers
    Opis:
    Purpose: This study was done to ascertain gender dif ferences in trained swimmers between their Critical S wim Speed (CSS). Certain metabolic responses, imme diately after 400 meters free style swimming (FSS), w ith maximum effort, were also studied. Methods: The analysis was conducted in trained swi mmers between 12- 18 years age. Height, weight, bod y fat quantity were estimated using standard techniqu es. CSS was measured for each swimmer. Blood samp les were taken within two minutes of 400 meters FSS, with maximum efforts. The blood creatinine, lactic ac id, serum calcium, serum urea and serum urea nitroge n were estimated using standard laboratory methods. Results: With the maximal effort of 400 meters FSS, values of hematological variables for both sexes were found to increase many folds than reference values. Si gnificant (p<0.05) gender differences were observed in CSS and blood creatinine. The positive significant (p<0.05) correlation was found between CSS and heig ht in the swimmers. For trained male swimmers signif icant positive correlations among CSS, blood urea an d serum urea nitrogen were found. Conclusions: This study reflects metabolic status of b oth trained male and female swimmers, after their full efforts. Besides blood creatinine no significant differe nces were observed in them. So it may conclude that e ffective physical training minimizes the metabolic de mands during their full efforts and gender differences could be overcome.
    Źródło:
    Progress in Health Sciences; 2016, 6(2); 46-50
    2083-1617
    Pojawia się w:
    Progress in Health Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Barriers in the Advancement of Solar Energy in Developing Countries like India
    Bariery w rozwoju energii słonecznej w krajach rozwijających się na przykładzie Indii
    Autorzy:
    Chakraborty, S.
    Sadhu, P. K.
    Goswami, U.
    Powiązania:
    https://bibliotekanauki.pl/articles/371096.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Komitet Człowiek i Środowisko PAN
    Tematy:
    solar energy
    solar market
    renewable energy
    energia słoneczna
    rynek energii solarnej
    energia odnawialna
    Opis:
    The present paper puts an emphasis on the current energy market scenario and different types of barriers associated with the advancement of solar energy in a developing countries like India. Solar energy, best suited for urban environment, can be housed in a limited space and is characterized as a pollution free, environmentally friendly, as well as noise-free source of electricity. Among the available renewable energies, solar energy is considered to be an integral one, owing to its reduction in cost at an exponential rate day-by-day. The present study deals with the potential of solar energy market in the Indian subcontinent along with several other problems that it needs to overcome in order to be established as an independent system.
    Artykuł omawia scenariusze związane ze współczesnym rynkiem energetycznym, wskazując na różnorodne typy barier, na które napotyka rozwój energii solarnej w krajach rozwijających się, takich jak Indie. Energia słoneczna doskonale sprawdza się w warunkach miejskich, przeznaczone do jej pozyskiwania instalacje nie potrzebują dużo miejsca i nie zanieczyszczają powietrza, a ponadto nie emitują hałasu. Wśród różnorodnych źródeł energii to właśnie energia solarna wydaje się być najbardziej korzystna, biorąc pod uwagę jej nieustannie malejące koszty. Niniejsza praca przedstawia potencjał rozwoju rynku energii słonecznej w Indiach, zwracając szczególna uwagę na problemy, które należy rozwiązać, aby mógł on funkcjonować, jako niezależny system.
    Źródło:
    Problemy Ekorozwoju; 2016, 11, 2; 75-80
    1895-6912
    Pojawia się w:
    Problemy Ekorozwoju
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Photocatalytic degradation of malachite green dye using doped and undoped ZnS nanoparticles
    Autorzy:
    Tolia, J.
    Chakraborty, M.
    Murthy, Z. V. P.
    Powiązania:
    https://bibliotekanauki.pl/articles/779662.pdf
    Data publikacji:
    2012
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    metoda mechanochemiczna
    zaawansowany proces utlenienia
    degradacja fotokatalityczna
    malachit zielony
    nanocząstki
    mechanochemical method
    advanced oxidation process
    photocatalytic degradation
    malachite green
    nanoparticles
    Opis:
    In the present study, ZnS nanoparticles were prepared using the mechanochemical method. The ZnS nanoparticles prepared were doped with different concentrations of manganese using metal acetate and manganese acetate by mechanochemical method. The as-prepared particles were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The photocatalytic activity of the prepared nanoparticles samples, in the photocatalytic degradation of malachite green, had been investigated. The nanoparticles were photo induced, generating hole transfer for photocatalytic activity. The photodegradation of malachite green was observed at different pH (2-5) values, dye concentrations (10-100mg/L) and amount of ZnS nanoparticles (1-2.5 g/L). About 95% degradation of dye was observed on the addition of 2 g/L ZnS in 50 mg/L dye solution after 90 minutes illumination at 125 W. Degradation has been increased up to 99% using UV/nanoparticles/H2O2 (50 mL/L) combined process. The degradation efficiency was also compared using Mn doped ZnS nanoparticles (Zn1-x MnxS, where x = 0.01, 0.22 and 0.3). Maximum of 97% degradation was observed with 0.01% concentration of Mn. Kinetics study and performance of UV/ZnS, UV/ZnS/H2O2, UV/doped ZnS processes were evaluated to compare the efficiency of different processes.
    Źródło:
    Polish Journal of Chemical Technology; 2012, 14, 2; 16-21
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    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:
    Sampling Properties of Estimators of Nucleotide Diversity at Discovered snp Sites
    Autorzy:
    Renwick, A.
    Bonnen, P. E.
    Trikka, D.
    Nelson, D. L.
    Chakraborty, R.
    Kimmel, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/908150.pdf
    Data publikacji:
    2003
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    genetyka
    statystyka
    single nucleotide polymorphisms
    ascertainment bias
    nucleotide diversity
    molecular evolution
    Opis:
    SNP sites are generally discovered by sequencing regions of the human genome in a limited number of individuals. This may leave SNP sites present in the region, but containing rare mutant nucleotides, undetected. Consequently, estimates of nucleotide diversity obtained from assays of detected SNP sites are biased. In this research we present a statistical model of the SNP discovery process, which is used to evaluate the extent of this bias. This model involves the symmetric Beta distribution of variant frequencies at SNP sites, with an additional probability that there is no SNP at any given site. Under this model of allele frequency distributions at SNP sites, we show that nucleotide diversity is always underestimated. However, the extent of bias does not seem to exceed 10-15% for the analyzed data. We find that our model of allele frequency distributions at SNP sites is consistent with SNP statistics derived based on new SNP data at ATM, BLM, RQL and WRN gene regions. The application of the theory to these new SNP data as well as to the literature data at the LPL gene region indicates that in spite of ascertainment biases, the observed differences of nucleotide diversity across these gene regions are real. This provides interesting evidence concerning the heterogeneity of the rates of nucleotide substitution across the genome.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2003, 13, 3; 385-394
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Identifying overlapping phylogenetic and geographic roots of HIV - 1 evolution through computational analyses
    Autorzy:
    Singh, P.K.
    Banik, R.
    Chakraborty, H.J.
    Das, S.G.
    Ganguli, S.
    Datta, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/11359.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    phylogenetic root
    geographic root
    evolution
    computational analysis
    HIV-1
    genome
    recombinant strain
    AIDS
    human disease
    acquired immunodeficiency syndrome zob.AIDS
    acquired immune deficiency syndrome zob.AIDS
    Opis:
    HIV-1 or Human Immuno Deficiency Virus-1 is the main causative agent of Acquired Immuno Deficiency Syndrome (AIDS). Human host infected with HIV - 1 extensively harbours many viral variants but very little is known about the difference in pattern[17] of evolution of phylogenetic lineages of HIV-1 non recombinant, normal inter subtype recombinant and main two specific recombinant forms of HIV-1 i.e., Circulating Recombinant Forms (CRFs) and Unique Recombinant Forms (URFs). This study is mainly concerned with study of the difference in evolutionary lineages of non-recombinant and recombinant sequences of HIV-1 genome sequences and identification of geographically rich areas which has reported high degree of HIV-1 occurrence and variety. Total 1550 HIV-1 genome sequences were obtained from HIV Los Alamos Database. The sequences were aligned using MAFFT (Multiple Alignment using Fast Fourier Transform) web server tool. Alignment was carried out using 10 different set of alignment parameter values. After alignment the aligned file was used for constructing N-J phylogenetic tree using Clustal X2 tool. Phylogenetic analysis was performed keeping in mind the category to which the sequence belongs. Upon analysis it was observed that the clade containing the probable ancestor belongs remained constant in all cases of different alignment values. Non recombinant isolates, inter subtype recombinants, CRFs, URFs all followed different patterns of evolution. Non recombinant sequences were found geographically specific and subtype specific to some extent whereas, normal recombinants were subtype specific and less geographically specific. CRFs showed variation among the pattern of their evolution. At some instances the sequences occurred as sister taxa of non-recombinant or normal inter subtype recombinant sequences, while at some instances as sister taxa of other CRFs where they were geographically specific. Three CRFs existed as completely diverged sequences. URFs were four in number; two of them were Indian isolates of while other two were Japanese isolates. URFs were found to be totally geographically specific. Geography wise high rate of variation was observed in India and Japan as these two countries had sequences belonging to all of the above categories. Cameroon and South Africa have very large number isolates and a considerable amount of genetic variation among isolates but they lack URFs.
    Źródło:
    International Letters of Natural Sciences; 2014, 02
    2300-9675
    Pojawia się w:
    International Letters of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Soil temperature prediction from air temperature for alluvial soils in lower Indo-Gangetic plain
    Autorzy:
    Barman, D.
    Kundu, D.K.
    Pal, S.
    Chakraborty, A.K.
    Jha, A.K.
    Mazumdar, S.P.
    Saha, R.
    Bhattacharyya, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/25358.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Opis:
    Soil temperature is an important factor in biogeochemical processes. On-site monitoring of soil temperature is limited in spatio-temporal scale as compared to air temperature data inventories due to various management difficulties. Therefore, empirical models were developed by taking 30-year long-term (1985-2014) air and soil temperature data for prediction of soil temperatures at three depths (5, 15, 30 cm) in morning (0636 Indian standard time) and afternoon (1336 Indian standard time) for alluvial soils in lower Indo-Gangetic plain. At 5 cm depth, power and exponential regression models were best fitted for daily data in morning and afternoon, respectively, but it was reverse at 15 cm. However, at 30 cm, exponential models were best fitted for both the times. Regression analysis revealed that in morning for all three depths and in afternoon for 30 cm depth, soil temperatures (daily, weekly, and monthly) could be predicted more efficiently with the help of corresponding mean air temperature than that of maximum and minimum. However, in afternoon, prediction of soil temperature at 5 and 15 cm depths were more precised for all the time intervals when maximum air temperature was used, except for weekly soil temperature at 15 cm, where the use of mean air temperature gave better prediction.
    Źródło:
    International Agrophysics; 2017, 31, 1
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Charged Excitons in the Quantum Hall Regime
    Autorzy:
    Schüller, C.
    Broocks, K.-B.
    Schröter, P.
    Heyn, C.
    Heitmann, D.
    Bichler, M.
    Wegscheider, W.
    Apalkov, V. M.
    Chakraborty, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2038336.pdf
    Data publikacji:
    2004-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.35.-y
    71.30.+h
    71.35.Ji
    71.70.Ej
    Opis:
    We review our recent optical experiments on two-dimensional electron systems at temperatures below 1 K and under high magnetic fields. The two-dimensional electron systems are realized in modulation-doped GaAs-AlGaAs single quantum wells. Via gate electrodes the carrier density of the two-dimensional electron systems can be tuned in a quite broad range between about 1×10$\text{}^{10}$ cm$\text{}^{-2}$ and 2×10$\text{}^{11}$ cm$\text{}^{-2}$. In dilute two-dimensional electron systems, at very low electron densities, we observe the formation of negatively charged excitons in photoluminescence experiments. In this contribution we report about the observation of a dark triplet exciton, which is observable at temperatures below 1 K and for electron filling factors <1/3, i.e., in the fractional quantum Hall regime only. In experiments where we have increased the density of the two-dimensional electron systems so that a uniform two-dimensional electron system starts to form, we have found a strong energy anomaly of the charged excitons in the vicinity of filling factor 1/3. This anomaly was found to exist in a very narrow parameter range of the density and temperature, only. We propose a model where we assume that localized charged excitons and a uniform Laughlin liquid coexist. The localized charged exciton in close proximity to the Laughlin liquid leads to the creation of a fractionally-charged quasihole in the liquid, which can account for the experimentally observed anomaly.
    Źródło:
    Acta Physica Polonica A; 2004, 106, 3; 341-353
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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