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1.
Environ Sci Technol ; 53(9): 5249-5255, 2019 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-30993982

RESUMO

Using village-based rice processing plants in rural Bangladesh, this study considered how parboiling rice could be altered to reduce the content of the carcinogen inorganic arsenic. Parboiling is normally conducted with rough rice (i.e., where the husk is intact) that is soaked overnight at ambient temperatures, and then either steamed or boiled for ∼10 min, followed by drying. Across 13 geographically dispersed facilities it was found that a simple alteration parboiling wholegrain, instead of rough rice, decreased the inorganic arsenic content by 25% ( P = 0.002) in the final polished grain. Also, parboiling wholegrain had little impact on milling quality of the final polished rice. The wholegrain parboiling approach caused statistically significant median enrichment of calcium, by 213%; and a reduction in potassium, by 40%; with all other nutrient elements tested being unaffected. Milled parboiled rough rice had an enriched inorganic arsenic compared to nonparboiled milled rice, but parboiling of wholegrain rice did not enrich inorganic arsenic in the final milled product. Polished rice produced from the parboiling of both rough and wholegrain rice significantly reduced cadmium compared to nonparboiled polished rice, by 25%. This study also identified that trimethylarsine oxide and tretramethylarsonium are widely elevated in the husk and bran of rice and, therefore, gives new insights into the biogeochemical cycling of arsenic in paddy ecosystems.


Assuntos
Arsênio , Oryza , Bangladesh , Cálcio , Ecossistema
2.
Environ Sci Technol ; 51(21): 12210-12218, 2017 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-28977751

RESUMO

For arsenic speciation, the inputs for wet deposition are not well understood. Here we demonstrate that trimethylarsine oxide (TMAO) and inorganic arsenic are the dominant species in monsoonal wet deposition in the summer Indian subcontinent, Bangladesh, with inorganic arsenic dominating, accounting for ∼80% of total arsenic in this medium. Lower concentrations of both species were found in monsoonal wet deposition in the winter Indian subcontinent, Sri Lanka. The only other species present was dimethylarsinic acid (DMAA), but this was usually below limits of detection (LoD). We hypothesize that TMAO and inorganic arsenic in monsoonal wet deposition are predominantly of marine origin. For TMAO, the potential source is the atmospheric oxidation of marine derived trimethylarsine. For inorganic arsenic, our evidence suggests entrainment of water column inorganic arsenic into atmospheric particulates. These conclusions are based on weather trajectory analysis and on the strong correlations with known wet deposition marine derived elements: boron, iodine, and selenium. The finding that TMAO and inorganic arsenic are widely present and elevated in monsoonal wet deposition identifies major knowledge gaps that need to be addressed regarding the understanding of arsenic's global cycle.


Assuntos
Arsênio , Arsenicais , Bangladesh , Ácido Cacodílico , Sri Lanka
3.
Vet World ; 17(2): 245-254, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38595663

RESUMO

Background and Aim: Campylobacter infections in sheep may be asymptomatic or cause enteritis, ileitis, infertility, and abortion. Thus, this study aimed to estimate the prevalence of Campylobacter spp. in farming sheep and to detect risk factors, molecular patterns, and antimicrobial susceptibility status of these pathogens. Materials and Methods: Four hundred and eight fecal samples were collected from 12 flocks in the Mymensingh and Sherpur districts. Samples were tested by both basic (culture and biochemical tests) and molecular (initially 16S rRNA and later hipO gene-based polymerase chain reaction). Furthermore, the antimicrobial susceptibility status of Campylobacter jejuni was confirmed using disk diffusion. Flock- and animal-level data were captured using semi-structured interviews with farm owners under bivariate and multivariate logistic regression analyses to confirm the risk factors for Campylobacter-positive status. Results: The prevalence of C. jejuni staining at the animal and flock levels was 8.82% (36/408) and 66.70% (8/12), respectively. The age of sheep was identified as an important risk factor. Up to 1 year of age, sheep were 3.78 times more likely to be infected with C. jejuni (95% confidence interval: 1.0736-13.3146, p = 0.038). Of the 36 isolates of C. jejuni, all were found to be fully susceptible (100%) to gentamicin and ciprofloxacin. In this study, three antimicrobial agents, oxytetracycline, azithromycin, and ceftriaxone, were fully resistant (100%). The majority of isolates were resistant to a combination of 4-6 antimicrobial agents. Conclusion: The present study highlights the predominant maintenance of zoonotic Campylobacter species in sheep, and their burden on human health is enormous. Therefore, environmental, animal, and human health needs to be focused under a One Health lens to mitigate the occurrence of Campylobacter in farm settings and to prevent further introduction to animals and humans.

4.
Radiat Prot Dosimetry ; 200(2): 130-142, 2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-37961917

RESUMO

Previously, we have developed DynamicMC for modeling relative movement of Oak Ridge National Laboratory phantom in a radiation field for the Monte Carlo N-Particle package (Health Physics. 2023,124(4):301-309). Using this software, three-dimensional dose distributions in a phantom irradiated by a certain mono-energetic (Mono E) source can be deduced through its graphical user interface. In this study, we extended DynamicMC to be used in combination with the Particle and Heavy Ion Transport code System (PHITS) by providing it with a higher flexibility for dynamic movement for an anthropomorphic phantom. For this purpose, we implemented four new functions into the software, which are (1) to generate not only Mono E sources but also those having an energy spectrum of an arbitrary radioisotope (2) to calculate the absorbed doses for several radiologically important organs (3) to automatically average the calculated absorbed doses along the path of the phantom and (4) to generate user-defined slab shielding materials. The first and third items utilize the PHITS-specific modalities named radioisotope-source and sumtally functions, respectively. The computational cost and complexity can be dramatically reduced with these features. We anticipate that the present work and the developed open-source tools will be in the interest of nuclear radiation physics community for research and teaching purposes.


Assuntos
Física Médica , Radiometria , Radiometria/métodos , Física Médica/métodos , Software , Movimento , Imagens de Fantasmas , Radioisótopos , Método de Monte Carlo
5.
Curr Probl Cardiol ; : 102755, 2024 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-39079620

RESUMO

AIMS: We aim to research the efficacy and safety of single(SAPT), dual(DAPT), and triple(TAPT) antiplatelets approaches across IHD patients undergoing PCI. METHODS AND RESULTS: A network meta-analysis was conducted until April 1st, 2024, using the netmeta package in R studio 4.3.3. Primary outcomes were cardiac death, myocardial infarction(MI), stent thrombosis, stroke, and major bleeding(BARC 3-5). From 25 studies, a total of 65115 patients were included. For cardiac death, TAPT had no different risk than DAPT compared to SAPT [RR = 0.74; 95%CI (0.40 to 1.35); p-value = 0.33], [RR = 1.01, 95%CI (0.84 to 1.19); p-value = 0.87] respectively. For MI, TAPT had no different risk than DAPT compared to SAPT [RR = 0.77; 95%CI (0.51 to 1.16); p-value = 0.2047], [RR = 0.81, 95%CI (0.64 to 1.03); p-value = 0.0850] respectively. For stent thrombosis, DAPT had no different risk than TAPT compared to SAPT [RR = 0.74; 95%CI (0.45 to 1.21); p-value = 0.2284], [RR = 0.84, 95%CI (0.27 to 2.59); p-value = 0.7630] respectively. For stroke, DAPT had no different risk than TAPT in comparison to SAPT [RR = 0.91; 95%CI (0.75 to 1.10); p-value = 0.3209], and [RR = 0.87, 95%CI (0.43 to 1.76); p-value=0.6937], respectively. For Major bleeding(BARC 3-5), DAPT and TAPT increased major bleeding compared to SAPT, with only DAPT showing statistical significance. [RR = 1.43; 95%CI (1.09 to 1.88); p-value = 0.0107], and [RR = 2.78, 95%CI (0.90 to 4.78); p-value = 0.0852], respectively. CONCLUSION: DAPT and TAPT increased the risk of bleeding events compared to SAPT. However, we found no significant differences between these regimens for the other primary outcomes.

6.
Expo Health ; 16(1): 87-99, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38313597

RESUMO

In Bangladesh most agronomic biomass (straw, husk, dried dung) is burnt for domestic cooking use. Consequently, the soil is continuously stripped of mineral nutrients and carbon (C) substrate. Here we investigate if recycling of household ash (ash) as fertilizer can sustainably improve soil fertility as well as minimise accumulation of toxic elements (As, Cd) in rice grain. Large scale field trials across two geographic regions (Barind, Madhupur) and two seasons (wet, dry) and with application of 3 fertiliser treatments (NPKS, ash, NPKS + ash) were conducted. At the end of each season, the impact of region*season*treatment on soil microbial comunities, rice yield, and grain quality (As, Cd, nutrient elements) was assessed. When compared to conventional field application rates of NPKS (control), application of ash boosted rice yield by circa. 20% in both regions during wet and dry season, with no effect on rice grain carcinogenic inorganic arsenic (iAs), dimethylarsonic acid (DMA) or cadmium (Cd), but with potential to increase zinc (Zn). For soil microbial communities, a significant region and season effect as well as correlation with elements in rice grain was observed, amongst these Cd, Zn, iAs and DMA. This study illustrates that application of ash can reduce the requirement for expensive chemical fertiliser, whilst at the same time increasing rice yield and maintaining grain quality, making farming in Bangladesh more sustainable and productive. The study also implies that the combined impact of region, season, and soil microbes determines accumulation of elements in rice grain. Supplementary Information: The online version contains supplementary material available at 10.1007/s12403-023-00539-y.

7.
Environ Sci Technol ; 47(11): 5613-8, 2013 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-23668419

RESUMO

Cereal grains are the dominant source of cadmium in the human diet, with rice being to the fore. Here we explore the effect of geographic, genetic, and processing (milling) factors on rice grain cadmium and rice consumption rates that lead to dietary variance in cadmium intake. From a survey of 12 countries on four continents, cadmium levels in rice grain were the highest in Bangladesh and Sri Lanka, with both these countries also having high per capita rice intakes. For Bangladesh and Sri Lanka, there was high weekly intake of cadmium from rice, leading to intakes deemed unsafe by international and national regulators. While genetic variance, and to a lesser extent milling, provide strategies for reducing cadmium in rice, caution has to be used, as there is environmental regulation as well as genetic regulation of cadmium accumulation within rice grains. For countries that import rice, grain cadmium can be controlled by where that rice is sourced, but for countries with subsistence rice economies that have high levels of cadmium in rice grain, agronomic and breeding strategies are required to lower grain cadmium.


Assuntos
Cádmio/análise , Contaminação de Alimentos/análise , Oryza/química , Oryza/genética , Bangladesh , Cádmio/toxicidade , China , Dieta , Exposição Ambiental , Variação Genética , Humanos , Índia , Sri Lanka
8.
J Nanosci Nanotechnol ; 13(11): 7707-11, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24245319

RESUMO

A facile approach was employed for the preparation of stable luminescent nanocomposites of CdS quantum dots (QDs) and polyacrylamide (PAM) through the cross coupling chemistry. Initially, CdS QDs were synthesized in a well controlled manner using 3-mercaptopropionic acid as a capping agent. Then, carboxylic acid groups on CdS QDs were chemically incorporated into PAM matrices with the assistance of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride and N-hydroxysulfosuccinimide coupling agents. FT-IR analysis was used to investigate the chemical incorporation of CdS QDs in PAM matrices via the covalent protocol. The XPS elemental mapping studies further suggested the formation of CdS-PAM nanocomposites. FE-SEM and TEM images were engaged to study the morphologies, and distribution of CdS QDs in the PAM networks. The physical structure of the CdS-PAM nanocomposites was investigated by XRD analysis. Thermal stability of the nanocomposites was observed to be enhanced in compare to PAM as evidenced from TGA data. The UV-vis and photoluminescence studies of the CdS-PAM nanocomposites suggested their promising optical applications.


Assuntos
Resinas Acrílicas/química , Compostos de Cádmio/síntese química , Cristalização/métodos , Luminescência , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Pontos Quânticos , Compostos de Selênio/síntese química , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Refratometria , Propriedades de Superfície , Condutividade Térmica
9.
J Nanosci Nanotechnol ; 13(1): 603-6, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23646782

RESUMO

Biocompatible magnetic nanocomposites of Fe-AuNPs and poly(2-hydroxylethyl methacrylate) (PHEMA) were employed as a strategic protein immobilization platform. The hybrid magnetic nanocomposites were prepared by applying a 'grafting to' ATRP protocol. Fe-AuNPs having Fe core and Au shell were initially prepared by the inverse micelle method. Disulfide-containing PHEMA (DT-PHEMA) was grafted to the Fe-AuNPs surface by taking the advantages of the thiol chemistry. The grafting of DT-PHEMA to the Fe-AuNPs was confirmed by relevant spectroscopic analyses. The superparamagnetic property, a basic requirement for facile protein immobilization, of the magnetic nanocomposites was measured by the SQUID analysis. Lysozyme, gamma-globulins and bovine serum albumin (BSA) were immobilized onto magnetic nanocomposites via the adsorption strategy. The absorption intensity of lysozyme, gamma-globulins and BSA on the PHEMA grafted Fe-AuNPs were observed to be higher than that of bare Fe-AuNPs.


Assuntos
Ouro/química , Ferro/química , Nanopartículas Metálicas/química , Poli-Hidroxietil Metacrilato/química , Proteínas/química , Adsorção , Teste de Materiais , Nanopartículas Metálicas/ultraestrutura , Conformação Molecular , Porosidade , Ligação Proteica , Proteínas/ultraestrutura , Propriedades de Superfície
10.
J Nanosci Nanotechnol ; 13(1): 694-7, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23646799

RESUMO

ZnO nanoparticles were covalently wrapped by polystyrene (PS) through surface thiol-lactam initiated radical polymerization using the grafting from approach. The surface of ZnO nanoparticles was initially modified by 3-mercapto propyltrimethoxysilane to afford thiol functionalized ZnO nanoparticles (ZnO-SH). The controlled radical polymerization of styrene (St) was subsequently accomplished by using an initiating system of ZnO-SH and butyrolactam. FT-IR, XPS, XRD, TGA, DSC, TEM and DLS were employed to investigate the chemical structure, morphology, thermal properties, the size and size distribution of nanocomposites. The dispersibility of ZnO nanoparticles was observed to be significantly improved upon functionalization by PS brushes. The controlled nature of the surface initiated thiol-lactam aided polymerization of St from the ZnO nanoparticles surface was confirmed by GPC analysis.


Assuntos
Cristalização/métodos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Poliestirenos/química , Óxido de Zinco/química , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
11.
ACS Omega ; 8(39): 35845-35855, 2023 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-37810722

RESUMO

The experiment was conducted at the research field, Department of Agronomy, Hajee Mohammad Danesh Science and Technology University, Dinajpur from December 2017 to May 2018 to find out the best treatment of foliar application of urea on the growth and yield of boro rice cv. BRRI dhan28. The experiment consisted of 10 treatments, laid out in a randomized complete block design in triplicate. The recommended doses (RD) of urea, TSP, MOP, gypsum, ZnSO4, and borax were applied during land preparation except for urea at 250, 75, 100, 75, 7, and 5 kg ha-1, respectively, where urea was applied as per treatment specification. The results revealed that the application of N fertilizer as foliage along with soil significantly influenced the growth, plant characteristics, and yield of BRRI dhan28. There was no significant difference between T8 (70% in soil and 10% as foliage) and T9 (100% in soil) treatment regarding the maximum panicle length (21.43 and 20.71 cm), fertile grains (117.40 and 113.30), total grains (134.40 and 130.97), 1000-grain weight (24.56 and 23.56 g), grain yield (5.91 and 5.74 t ha-1), straw yield (7.83 and 7.92 t ha-1), biological yield (13.74 and 13.66 t ha-1), and harvest index (43.01 and 42.02%), respectively, in this study. These results indicated that N fertilization as direct soil application (70%) and as foliage application (10%), i.e., 80% N fertilization, produced the highest grain yield and major yield traits which we received by 100% N fertilization as soil that was practiced traditionally by the farmers. The effect of overfertilization (T10) was not positive, producing the highest number of noneffective tillers and sterile grains (nonfilled grains). Therefore, it is possible to achieve an equivalent or more yield by saving 20% urea by the combination of soil (70%) and foliage (10%) application as compared to the traditional method of fertilizer application (100% in soil).

12.
Avian Pathol ; 41(2): 133-9, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22515532

RESUMO

Infectious bursal disease virus (IBDV) is the aetiological agent of the acute and highly contagious infectious bursal disease (IBD) or "Gumboro disease". IBD is one of the economically most important diseases that affects commercially produced chickens worldwide. Along with strict hygiene management of poultry farms, vaccination programmes with inactivated and live attenuated viruses have been used to prevent IBD. Live vaccines show a different degree of attenuation; many of them may cause bursal atrophy and thus immunosuppression with poor immune response to vaccination against other pathogens and an increase in vulnerability to various types of infections as possible consequences. Depending on their intrinsic characteristics or on the vaccination procedures, some of the vaccines may not induce full protection against the very virulent IBDV strains and antigenic variants observed in the last three decades. As chickens are most susceptible to IBDV in their first weeks of life, active immunity to the virus has to be induced early after hatching. However, maternally derived IBDV-specific antibodies may interfere with early vaccination with live vaccines. Thus new technologies and second-generation vaccines including rationally designed and subunit vaccines have been developed. Recently, live viral vector vaccines have been licensed in several countries and are reaching the market. Here, the current status of IBD vaccines is discussed.


Assuntos
Anticorpos Antivirais/imunologia , Infecções por Birnaviridae/veterinária , Galinhas , Vírus da Doença Infecciosa da Bursa/imunologia , Doenças das Aves Domésticas/prevenção & controle , Doenças das Aves Domésticas/virologia , Vacinas Virais/imunologia , Animais , Infecções por Birnaviridae/prevenção & controle , Engenharia Genética/métodos , Vacinas Atenuadas/imunologia
13.
J Nanosci Nanotechnol ; 12(7): 5976-80, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22966692

RESUMO

An approach to the surface modification of TiO2 nanoparticles was described based on the thiol functionalization of TiO2 followed by thiol-lactam initiated radical polymerization (TLIRP) of methyl methacrylate (MMA). FT-IR, XRD and XPS analyses confirmed the grafting of the polymer on the TiO2 surface. TGA analysis revealed superior thermal stability of PMMA-g-TiO2 compared with PMMA. TEM measurements and time-dependent phase monitoring suggested much higher colloidal stability of PMMA-g-TiO2 than TiO2 in toluene. The controlled nature of the TLIRP of MMA from the surface of TiO2 was determined by GPC analysis.

14.
J Radiat Res ; 63(3): 385-392, 2022 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-35349714

RESUMO

The Monte Carlo (MC) method is a powerful tool for modeling nuclear radiation interaction with matter. A variety of MC software packages has been developed, especially for applications in radiation therapy. Most widely used MC packages require users to write their own input scripts for their systems, which can be a time consuming and error prone process and requires extensive user experience. In the present work, we have developed a graphical user interface (GUI) bundled with a custom-made 3D OpenGL visualizer for PHITS MC package. The current version focuses on modeling proton induced positron emitting radioisotopes, which in turn can be used for verification of proton ranges in proton therapy. The developed GUI program does not require extensive user experience. The present open-source program is distributed under GPLv3 license that allows users to freely download, modify, recompile and redistribute the program.


Assuntos
Terapia com Prótons , Elétrons , Método de Monte Carlo , Prótons , Radioisótopos , Software
15.
PLoS One ; 17(5): e0267610, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35639785

RESUMO

The interaction of ionizing radiation with matter is a stochastic process and statistical analysis of such a process would be a crucial step in understanding radioactivity. Geiger-Müller (GM) counter is a widely used radiation detector used in nuclear radiation surveying, which produces counts upon exposure to a radioactive source. There are a variety of multi-purpose software that can be used to perform statistical analysis of measured counts from a GM counter. However, statistical analysis is a lengthy, error prone and time-consuming process, which gets more tedious when the number of measurements increases. In the present work, we have developed an open-source and easy-to-use graphical user interface (GUI) computer program named RadStat for statistical analysis of counts measured by a GM counter. RadStat has its own scripting syntaxes and bundled with gnuplot for quick visualization of output results. We believe the present open-source GUI program would be a useful tool for research and teaching of nuclear radiation physics.


Assuntos
Radiometria , Software , Projetos de Pesquisa , Processos Estocásticos
16.
Sci Rep ; 12(1): 18098, 2022 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-36302927

RESUMO

The present work introduced a framework to investigate the effectiveness of proton boron fusion therapy (PBFT) at the cellular level. The framework consisted of a cell array generator program coupled with PHITS Monte Carlo package with a dedicated terminal-based code editor that was developed in this work. The framework enabled users to model large cell arrays with normal, all boron, and random boron filled cytoplasm, to investigate the underlying mechanism of PBFT. It was found that alpha particles and neutrons could be produced in absence of boron mainly because of nuclear reaction induced by proton interaction with 16O, 12C and 14N nuclei. The effectiveness of PBFT is highly dependent on the incident proton energy, source size, cell array size, buffer medium thickness layer, concentration and distribution of boron in the cell array. To quantitatively assess the effectiveness of PBFT, of the total energy deposition by alpha particle for different cases were determined. The number of alpha particle hits in cell cytoplasm and nucleus for normal and 100 ppm boron were determined. The obtained results and the developed tools would be useful for future development of PBFT to objectively determine the effectiveness of this treatment modality.


Assuntos
Terapia por Captura de Nêutron de Boro , Terapia com Prótons , Boro , Terapia por Captura de Nêutron de Boro/métodos , Prótons , Nêutrons , Método de Monte Carlo
17.
PeerJ ; 10: e12862, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35186468

RESUMO

BACKGROUND: Mungbean (Vigna radiata L. Wilczek) is one of the most important pulse crops, well-known for its protein-rich seeds. Growth and productivity are severely undermined by waterlogging. METHODS: In this study, we aim to evaluate how two promising phytohormones, namely cytokinin (CK) and gibberellic acid (GA3), can improve waterlogging tolerance in mungbean by investigating key morphological, physiological, biochemical, and yield-related attributes. RESULTS: Our results showed that foliar application of CK and GA3 under 5-day of waterlogged conditions improved mungbean growth and biomass, which was associated with increased levels of photosynthetic rate and pigments. Waterlogged-induced accumulation of reactive oxygen species and the consequently elevated levels of malondialdehyde were considerably reduced by CK and GA3 treatments. Mungbean plants sprayed with either CK or GA3 suffered less oxidative stress due to the enhancement of total phenolics and flavonoids levels. Improvement in the contents of proline and total soluble sugars indicated a better osmotic adjustment following CK and GA3 treatments in waterlogged-exposed plants. Most fundamentally, CK or GA3-sprayed waterlogged-stressed mungbean plants demonstrated better performance in the aforementioned parameters after the 15-day recovery period as compared to water-sprayed waterlogged-exposed plants. Our results also revealed that CK and GA3 treatments increased yield-associated features in the waterlogged-stressed plant. Here, both phytohormones are efficient in improving mungbean resistance to waterlogging. However, CK was found to be more effective. Overall, our findings suggested that CK or GA3 could be used for managing waterlogging-induced damage to mungbean and perhaps in other cash crops.


Assuntos
Fabaceae , Vigna , Reguladores de Crescimento de Plantas/farmacologia , Citocininas/farmacologia
18.
PLoS One ; 17(2): e0263521, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35167589

RESUMO

The Monte Carlo method is employed in this study to simulate the proton irradiation of a water-gel phantom. Positron-emitting radionuclides such as 11C, 15O, and 13N are scored using the Particle and Heavy Ion Transport Code System Monte Carlo code package. Previously, it was reported that as a result of 16O(p,2p2n)13N nuclear reaction, whose threshold energy is relatively low (5.660 MeV), a 13N peak is formed near the actual Bragg peak. Considering the generated 13N peak, we obtain offset distance values between the 13N peak and the actual Bragg peak for various incident proton energies ranging from 45 to 250 MeV, with an energy interval of 5 MeV. The offset distances fluctuate between 1.0 and 2.0 mm. For example, the offset distances between the 13N peak and the Bragg peak are 2.0, 2.0, and 1.0 mm for incident proton energies of 80, 160, and 240 MeV, respectively. These slight fluctuations for different incident proton energies are due to the relatively stable energy-dependent cross-section data for the 16O(p,2p2n)13N nuclear reaction. Hence, we develop an open-source computer program that performs linear and non-linear interpolations of offset distance data against the incident proton energy, which further reduces the energy interval from 5 to 0.1 MeV. In addition, we perform spectral analysis to reconstruct the 13N Bragg peak, and the results are consistent with those predicted from Monte Carlo computations. Hence, the results are used to generate three-dimensional scatter plots of the 13N radionuclide distribution in the modeled phantom. The obtained results and the developed methodologies will facilitate future investigations into proton range monitoring for therapeutic applications.


Assuntos
Radioisótopos de Nitrogênio/farmacologia , Terapia com Prótons/métodos , Algoritmos , Humanos , Método de Monte Carlo , Imagens de Fantasmas
19.
Environ Sci Technol ; 45(14): 6080-7, 2011 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-21692537

RESUMO

Agroecological zones within Bangladesh with low levels of arsenic in groundwater and soils produce rice that is high in arsenic with respect to other producing regions of the globe. Little is known about arsenic cycling in these soils and the labile fractions relevant for plant uptake when flooded. Soil porewater dynamics of field soils (n = 39) were recreated under standardized laboratory conditions to investigate the mobility and interplay of arsenic, Fe, Si, C, and other elements, in relation to rice grain element composition, using the dynamic sampling technique diffusive gradients in thin films (DGT). Based on a simple model using only labile DGT measured arsenic and dissolved organic carbon (DOC), concentrations of arsenic in Aman (Monsoon season) rice grain were predicted reliably. DOC was the strongest determinant of arsenic solid-solution phase partitioning, while arsenic release to the soil porewater was shown to be decoupled from that of Fe. This study demonstrates the dual importance of organic matter (OM), in terms of enhancing arsenic release from soils, while reducing bioavailability by sequestering arsenic in solution.


Assuntos
Arsênio/farmacocinética , Substâncias Húmicas/análise , Oryza/metabolismo , Solo/análise , Movimentos da Água , Agricultura , Análise de Variância , Arsênio/química , Bangladesh , Disponibilidade Biológica , Cromatografia Líquida de Alta Pressão , Difusão , Concentração de Íons de Hidrogênio , Espectrometria de Massas , Análise de Componente Principal , Análise de Regressão
20.
Environ Sci Technol ; 45(10): 4262-9, 2011 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-21504212

RESUMO

Arsenic (As) contamination of paddy soils threatens rice cultivation and the health of populations relying on rice as a staple crop. In the present study, isotopic dilution techniques were used to determine the chemically labile (E value) and phytoavailable (L value) pools of As in a range of paddy soils from Bangladesh, India, and China and two arable soils from the UK varying in the degree and sources of As contamination. The E value accounted for 6.2-21.4% of the total As, suggesting that a large proportion of soil As is chemically nonlabile. L values measured with rice grown under anaerobic conditions were generally larger than those under aerobic conditions, indicating increased potentially phytoavailable pool of As in flooded soils. In an incubation study, As was mobilized into soil pore water mainly as arsenite under flooded conditions, with Bangladeshi soils contaminated by irrigation of groundwater showing a greater potential of As mobilization than other soils. Arsenic mobilization was best predicted by phosphate-extractable As in the soils.


Assuntos
Arsênio/análise , Monitoramento Ambiental/métodos , Poluentes do Solo/análise , Agricultura , Arsênio/química , Fracionamento Químico/métodos , Água Doce/química , Isótopos/análise , Isótopos/química , Oryza , Solo/química , Poluentes do Solo/química
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