Fertilizer management should consider optimum time, rates and methods of application to increase use efficiency and crop yield. We conducted field experiments at Bangladesh Agricultural University, ...Bangladesh, to investigate the effects of deep placement of urea briquettes (UB) and NPK briquettes (NPK) compared to broadcast prilled urea (PU) at different N rates on dynamics of floodwater NH₄ ⁺-N, ammonia (NH₃) volatilization, rice yield and nitrogen use efficiency (NUE) during four consecutive rice-growing seasons in 2012–2013. The floodwater NH₄ ⁺-N and NH₃ volatilization in broadcast PU increased with N rates, while in deep-placed treatments irrespective of N rates it was similar to the control. Across seasons and water regime, UB or NPK significantly (P < 0.05) increased grain yield and nitrogen recovery compared to broadcast PU. During the Boro season (across water regime), UB78 and NPK78 increased grain yield by 40 and 29 %, respectively, compared to broadcast PU78, while N recovery increased from 35 % of PU to 63–67 % in deep placement. Deep placement of UB52 or NPK52 during Aus–Aman and UB78 or NPK78 during Boro can be one of the best N management options for increasing NUE and crop yield. Alternate wetting and drying irrigation, though, had no significant effect on grain yield or on NUE. Its adoption could save irrigation water without any yield reduction during the Boro season. However, more studies across different soils, climate and management practices are needed for further understanding the interactive effects of fertilizer and water management on yield, NUE and soil fertility.
Polyurethanes (PUs) are a class of versatile materials with great potential for use in different applications, especially based on their structure-property relationships. Their specific mechanical, ...physical, biological, and chemical properties are attracting significant research attention to tailoring PUs for use in different applications. Enhancement of the properties and performance of PU-based materials may be achieved through changes to the production process or the raw materials used in their fabrication or
via
the use of advanced characterization techniques. Clearly, modification of the raw materials and production process through proper methods can produce PUs that are suitable for varied specific applications. The present study aims to shed light on the chemistry, types, and synthesis of different kinds of PUs. Some of the important research studies relating to PUs, including their synthesis method, characterization techniques, and research findings, are comprehensively discussed. Herein, recent advances in new types of PUs and their synthesis for various applications are also presented. Furthermore, information is provided on the environmental friendliness of the PUs, with a specific emphasis on their recyclability and recoverability.
Polyurethanes (PUs) are a class of versatile materials with great potential for use in different applications, especially based on their structure-property relationships.
Urea deep placement (UDP) has demonstrated its benefits of saving N fertilizer and increasing nitrogen use efficiency (NUE) and grain yields. However, studies on its environmental impacts, ...particularly on nitrous oxide (N
2
O) and nitric oxide (NO), are limited. We conducted multi-location field experiments in Bangladesh to determine the effects of UDP versus broadcast prilled urea (PU) on N
2
O and NO emissions, NUE, and rice yields. N
2
O and NO emissions were measured from three N fertilizer treatments—no N, UDP, and PU—using automated gas sampling and analysis systems continuously for two rice-growing seasons—
Aus
(May–August) and
Aman
(August–December). Fertilizer-induced peaks in N
2
O emissions were observed after broadcast application of PU but were rarely observed after UDP. Total seasonal N
2
O and NO emissions, yield-scaled emissions, and fertilizer-induced emissions were affected by fertilizer treatments and sites. Though nitrogen fertilizer increased emissions significantly over the control, emissions resulting from UDP and PU were similar. Effects of N placement on grain yields and NUE were site- and season-specific. Of the N placement methods, UDP increased grain yields by 13% (
p
< 0.05) during the
Aman
season and gave similar yields in spite of lower N application during the
Aus
season. UDP increased N recovery from 25 and 16% of broadcast PU to 61 and 73% during the
Aus
and the
Aman
seasons, respectively in one site, but was similar in another site. On the other hand, alternate wetting and drying irrigation reduced grain yield and N recovery at the BRRI site during the
Aman
season.
Urea deep placement (UDP) increases nitrogen use efficiency (NUE) in lowland rice fields by reducing ammonia volatilization, surface runoff and increasing nitrogen uptake. However, its effects on N ...losses as nitrous oxide (N2O) and nitric oxide (NO) are not yet clear. We conducted field experiments at two locations of Bangladesh — Bangladesh Agricultural University (BAU) and Bangladesh Rice Research Institute (BRRI) — to determine the effects of UDP vs broadcast urea on N2O and NO emissions from rice fields.
N2O and NO emissions were measured from three N fertilizer treatments (control 0kgN/ha, UDP, broadcast urea) using automated gas sampling and analysis system continuously for three rice growing seasons — Aus (May–Aug), Aman (Aug–Dec) and Boro (Jan–May). Urea was applied as 2–3 split application, while for UDP treatment, urea briquettes were deep placed (7–10cm depth) between 4 hills of rice at alternate rows to meet recommended N rates in a single application. Treatments were arranged in a randomized complete block design with three replications and N2O and NO measurements were done at every three-hour interval.
N2O emissions were sporadic and event specific. Peaks in N2O emissions were observed after broadcast application of urea, during dry period and after re-flooding of the dry soil. For the rest of the time during the rice-growing season, emissions were very low to negligible. However, across the rice-growing seasons, UDP significantly (P<0.05) reduced N2O emissions compared with broadcast urea. Moreover, N2O emissions showed significant spatial and seasonal variations. They were higher during Boro season compared with Aus and Aman seasons and at BAU site than that of BRRI. Conversely, emissions between Aus and Aman seasons and between control and UDP treatments were similar. In contrast to N2O emissions, NO emissions were negligible and not affected by fertilizer treatment. However, significant spatial and seasonal variations were observed, with higher NO emissions at BRRI site compared with BAU and during Boro than that of Aus season.
•First automated continuous measurement of N2O and NO emissions from triple rice cropping system in Bangladesh•Comparison of N2O and NO emissions between urea deep placement (UDP) and broadcast urea application•Estimation of seasonal emission factors for N2O and NO emissions•Significant seasonal and spatial variations on N2O and NO emissions
In this paper, along with the progress of modern wind energy technology, the trends of wind energy technology and potential challenges have been studied thoroughly. It is estimated that within the ...next 2–3 decades, the Vertical Axis Wind Turbine (VAWT) can dominate the wind-energy technology. The VAWT requires less land space and using the same space; it is capable of producing more wind energy than that of its counterpart. By implying the Fish Schooling Concept effectively and successfully, it is possible to advance the wind-energy technology more. In the last 3–4 decades, the wind turbine capacity has been increased around 30–40 times. With the increase of wind energy capacity, the demand of the energy storage system has been increased significantly. Along with the many energy storage systems, fuel cells and batteries are the two most promising devices to meet the demand in RE systems. The wind-energy technology is established itself but not yet fully mature and hence there are many areas where improvements are required to reduce the cost of wind energy.
Pneumonia is a life-threatening disease, which occurs in the lungs caused by either bacterial or viral infection. It can be life-endangering if not acted upon at the right time and thus the early ...diagnosis of pneumonia is vital. The paper aims to automatically detect bacterial and viral pneumonia using digital x-ray images. It provides a detailed report on advances in accurate detection of pneumonia and then presents the methodology adopted by the authors. Four different pre-trained deep Convolutional Neural Network (CNN): AlexNet, ResNet18, DenseNet201, and SqueezeNet were used for transfer learning. A total of 5247 chest X-ray images consisting of bacterial, viral, and normal chest x-rays images were preprocessed and trained for the transfer learning-based classification task. In this study, the authors have reported three schemes of classifications: normal vs. pneumonia, bacterial vs. viral pneumonia, and normal, bacterial, and viral pneumonia. The classification accuracy of normal and pneumonia images, bacterial and viral pneumonia images, and normal, bacterial, and viral pneumonia were 98%, 95%, and 93.3%, respectively. This is the highest accuracy, in any scheme, of the accuracies reported in the literature. Therefore, the proposed study can be useful in more quickly diagnosing pneumonia by the radiologist and can help in the fast airport screening of pneumonia patients.
A review on global solar energy policy Solangi, K.H.; Islam, M.R.; Saidur, R. ...
Renewable & sustainable energy reviews,
05/2011, Letnik:
15, Številka:
4
Journal Article
Recenzirano
To overcome the negative impacts on the environment and other problems associated with fossil fuels have forced many countries to inquire into and change to environmental friendly alternatives that ...are renewable to sustain the increasing energy demand. Solar energy is one of the best renewable energy sources with least negative impacts on the environment. Different countries have formulated solar energy policies to reducing dependence on fossil fuel and increasing domestic energy production by solar energy. This paper discusses a review about the different solar energy policies implemented on the different countries of the world. According to the 2010 BP Statistical Energy Survey, the world cumulative installed solar energy capacity was 22928.9
MW in 2009, a change of 46.9% compared to 2008. Also this paper discussed the existing successful solar energy policies of few selected countries. Based on literatures, it has been found that FIT, RPS and incentives are the most beneficial energy policies implemented by many countries around the world. These policies provide significant motivation and interest for the development and use of renewable energy technologies. Also the status of solar energy policy for Malaysia is investigated and compared with that of the successful countries in the world.
Connective tissue mechanics is highly nonlinear, exhibits a strong Poisson's effect, and is associated with significant collagen fiber re-arrangement. Although the general features of the ...stress-strain behavior have been discussed extensively, the Poisson's effect received less attention. In general, the relationship between the microscopic fiber network mechanics and the macroscopic experimental observations remains poorly defined. The objective of the present work is to provide additional insight into this relationship. To this end, results from models of random collagen networks are compared with experimental data on reconstructed collagen gels, mouse skin dermis, and the human amnion. Attention is devoted to the mechanism leading to the large Poisson's effect observed in experiments. The results indicate that the incremental Poisson's contraction is directly related to preferential collagen orientation. The experimentally observed downturn of the incremental Poisson's ratio at larger strains is associated with the confining effect of fibers transverse to the loading direction and contributing little to load bearing. The rate of collagen orientation increases at small strains, reaches a maximum, and decreases at larger strains. The peak in this curve is associated with the transition of the network deformation from bending dominated, at small strains, to axially dominated, at larger strains. The effect of fiber tortuosity on network mechanics is also discussed, and a comparison of biaxial and uniaxial loading responses is performed.
Water is synonymous with life. This has been the case since pre-historic time to the modern era. For the first time, humanity faces a crisis that eclipses the energy crisis, which has often ...incapacitated the global economy. The Climate-Water-Food nexus epitomizes our current civilization that depends on energy as the driver. Many recognize this crisis as a product of fossil fuel production, which allegedly triggered climate change and the "climate change debate." Others predict the onslaught of "water wars" in the coming decades. As the world gears up to another lineup of empty promises and ensuing chaos, this book turns this crisis on its head and shows the source of the water crisis. The science behind the water cycle is described in clear language, without resorting to dogmatic assertions and spurious assumptions. The role of the sun, natural carbon dioxide (CO2) and water and the need to maintain natural processes free from artificial chemicals are discussed in detail. The book makes it clear how most of the currently used purification techniques violates the natural cycle involving sunlight, CO2 and water, and thus become unsustainable.
Soil organic carbon (SOC), a core soil quality indicator, is influenced by management practices. The objective of our 2012-2016 study was to elucidate the impact of gypsum, crop rotation, and cover ...crop on SOC and several of its biological indicators under no-till in Alabama (Shorter), Indiana (Farmland), and Ohio (Hoytville and Piketon) in the USA. A randomized complete block design in factorial arrangement with gypsum (at 0, 1.1, and 2.2 Mg/ha annually), rye (Secale cereal L.) vs no cover crop, and rotation (continuous soybean Glycine max (L) Merr., SS vs corn Zea mays, L.-soybean, both the CS and SC phases) was conducted. Composite soils were collected (0-15 cm and 15-30 cm) in 2016 to analyze microbial biomass C (SMBC), SOC, total N, active C, cold and hot-water extractable C, C and N pool indices (CPI and NPI), and C management index (CMI). Results varied for main effects of gypsum, crop rotation, and cover crop on SOC pools, total N, and SOC lability within and across the sites. Gypsum at 2.2 Mg/ha increased SMBC within sites and by 41% averaged across sites. Likewise, gypsum increased SMBC:SOC, active C, and hot-water C (as indicators of labile SOC) averaged across sites. CS rotation increased SOC, active C, CPI, and CMI compared to SS, but decreased SMBC and SMBC:SOC within and across sites. CPI had a significant relationship with NPI across all sites (R2 = 0.90). Management sensitive SOC pools that responded to the combined gypsum (2.2 Mg/ha), crop rotation (CS), and cover crop (rye) were SMBC, SMBC:SOC, active C, and CMI via SMBC. These variables can provide an early indication of management-induced changes in SOC storage and its lability. Our results show that when SOC accumulates, its lability has decreased, presumably because the SMBC has processed all readily available C into a less labile form.
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