A critical and up-to-date review has been conducted on the latest individual valorization technologies aimed at the generation of value-added by-products from food wastes in the form of bio-fuels, ...bio-materials, value added components and bio-based adsorbents. The aim is to examine the associated advantages and drawbacks of each technique separately along with the assessment of process parameters affecting the efficiency of the generation of the bio-based products. Challenges faced during the processing of the wastes to each of the bio-products have been explained and future scopes stated. Among the many hurdles encountered in the successful and high yield generation of the bio-products is the complexity and variability in the composition of the food wastes along with the high inherent moisture content. Also, individual technologies have their own process configurations and operating parameters which may affect the yield and composition of the desired end product. All these require extensive study of the composition of the food wastes followed by their effective pre-treatments, judicial selection of the technological parameters and finally optimization of not only the process configurations but also in relation to the input food waste material. Attempt has also been made to address the hurdles faced during the implementation of such technologies on an industrial scale.
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•In-depth review on individual valorization techniques adopted for agro-food wastes.•Focus on parameter configuration, appropriate pre-treatment, input waste material.•Strategies involve conversion of food waste to biofuel, materials and adsorbents.•Attempt to focus on the technological hurdles during scale up of individual valorization.
This review covers the current and emerging analytical methods used in laboratory, field, landscape and regional contexts for measuring soil organic carbon (SOC) sequestration in agricultural soil. ...Soil depth plays an important role in estimating SOC sequestration. Selecting appropriate sampling design, depth of soil, use of proper analytical methods and base line selection are prerequisites for estimating accurately the soil carbon stocks. Traditional methods of wet digestion and dry combustion (DC) are extensively used for routine laboratory analysis; the latter is considered to be the “gold standard” and superior to the former for routine laboratory analysis. Recent spectroscopic techniques can measure SOC stocks in laboratory and in-situ even up to a deeper depth. Aerial spectroscopy using multispectral and/or hyperspectral sensors located on aircraft, unmanned aerial vehicles (UAVs) or satellite platforms can measure surface soil organic carbon. Although these techniques' current precision is low, the next generation hyperspectral sensor with improved signal noise ratio will further improve the accuracy of prediction. At the ecosystem level, carbon balance can be estimated directly using the eddy-covariance approach and indirectly by employing agricultural life cycle analysis (LCA). These methods have tremendous potential for estimating SOC. Irrespective of old or new approaches, depending on the resources and research needed, they occupy a unique place in soil carbon and climate research. This paper highlights the overview, potential limitations of various scale-dependent techniques for measuring SOC sequestration in agricultural soil.
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•Methodologies for the measurement of soil carbon sequestration at point, field, ecosystem and regional level reviewed.•Recent developments in spectroscopic techniques are discussed.•Eddy-covariance and indirectly LCA methodological approaches are reviewed.•Methodological potentials and uncertainties of soil carbon research sequestration are highlighted.
Understanding the spatial spreading patterns of plant-available sulphur (S) (AS) and plant-available micronutrients (available zinc (AZn), available iron (AFe), available copper (ACu), available ...manganese (AMn) and available boron (AB)) in soils, especially in coastal agricultural soils subjected to various natural and anthropogenic activities, is vital for sustainable crop production by adopting site-specific nutrient management (SSNM) strategies. We studied the spatial distribution patterns of AS, AZn, AFe, ACu, AMn, and AB in cultivated soils of coastal districts of India using geostatistical approaches. Altogether 39,097 soil samples from surface (0 to 15 cm depth) layers were gathered from farm lands of 68 coastal districts. The analysis of soil samples was carried out for soil pH, electrical conductivity (EC), soil organic carbon (SOC) and AS, AZn, AFe, ACu, AMn, and AB. Soil pH, EC and SOC varied from 3.70 to 9.90, 0.01 to 7.45 dS m.sup.-1 and 0.02 to 3.74%, respectively. The concentrations of AS, AZn, AFe, ACu, AMn, and AB varied widely in the study area with their corresponding mean values were 37.4±29.4, 1.50±1.53, 27.9±35.1, 2.14±1.74, 16.9±18.4 and 1.34±1.52 mg kg.sup.-1, respectively. The coefficient of variation values of analyzed soil parameters varied from 14.6 to 126%. The concentrations of AS, AZn, AFe, ACu, AMn, and AB were negatively and significantly correlated with soil pH and positively and significantly correlated with SOC. The geostatistical analysis indicated stable, Gaussian and exponential best-fit semivariogram models with moderate to strong spatial dependence for available nutrients. The generated spatial spreading maps revealed different distribution patterns for AS, AZn, AFe, ACu, AMn, and AB. There were variations in spatial spreading patterns of AS, AZn, AFe, ACu, AMn, and AB in east- and west-coastal area. About 62, 35, 12, 0.4, 23 and 45% of the study area had deficiency of AS, AZn, AFe, ACu, AMn, and AB, respectively. The spatial spreading maps will be highly useful for SSNM in the cultivated coastal soils of the country. This study could also be used as a base for assessing spatial spreading patterns of soil parameters in cultivated coastal areas of other parts of the world.
Rice is one of the principal staple foods, essential for safeguarding the global food and nutritional security, but due to different natural and anthropogenic sources, it also acts as one of the ...biggest reservoirs of potentially toxic metal(loids) like As, Hg, Se, Pb and Cd. This review summarizes mobilization, translocation and speciation mechanism of these metal(loids) in soil-plant continuum as well as available cost-effective remediation measures and future research needs to eliminate the long-term risk to human health. High concentrations of these elements not only cause toxicity problems in plants, but also in animals that consume them and gradual deposition of these elements leads to the risk of bioaccumulation. The extensive occurrence of contaminated rice grains globally poses substantial public health risk and merits immediate action. People living in hotspots of contamination are exposed to higher health risks, however, rice import/export among different countries make the problem of global concern. Accumulation of As, Hg, Se, Pb and Cd in rice grains can be reduced by reducing their bioavailability, and controlling their uptake by rice plants. The contaminated soils can be reclaimed by phytoremediation, bioremediation, chemical amendments and mechanical measures; however these methods are either too expensive and/or too slow. Integration of innovative agronomic practices like crop establishment methods and improved irrigation and nutrient management practices are important steps to help mitigate the accumulation in soil as well as plant parts. Adoption of transgenic techniques for development of rice cultivars with low accumulation in edible plant parts could be a realistic option that would permit rice cultivation in soils with high bioavailability of these metal(loid)s.
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•Mobilization, translocation and speciation mechanism of metal(loids) were discussed.•Mitigation opportunities are reviewed to explore the future research needs.•Genetic approaches are promising for reducing accumulation in grains.•Health risk assessment was done.
Rice-rice system and rice fallows are no longer productive in Southeast Asia. Crop and varietal diversification of the rice based cropping systems may improve the productivity and profitability of ...the systems. Diversification is also a viable option to mitigate the risk of climate change. In Eastern India, farmers cultivate rice during rainy season (June-September) and land leftovers fallow after rice harvest in the post-rainy season (November-May) due to lack of sufficient rainfall or irrigation amenities. However, in lowland areas, sufficient residual soil moistures are available in rice fallow in the post-rainy season (November-March), which can be utilized for raising second crops in the region. Implementation of suitable crop/varietal diversification is thus very much vital to achieve this objective. To assess the yield performance of rice varieties under timely and late sown conditions and to evaluate the performance of dry season crops following them, three different duration rice cultivars were transplanted in July and August. In dry season several non-rice crops were sown in rice fallow to constitute a cropping system. The results revealed that tiller occurrence, biomass accumulation, dry matter remobilization, crop growth rate, and ultimately yield were significantly decreased under late transplanting. On an average, around 30% yield reduction obtained under late sowing may be due to low temperature stress and high rainfall at reproductive stages of the crop. Dry season crops following short duration rice cultivars performed better in terms of grain yield. In the dry season, toria was profitable when sown earlier and if sowing was delayed greengram was suitable. Highest system productivity and profitability under timely sown rice may be due to higher dry matter remobilization from source to sink. A significant correlation was observed between biomass production and grain yield. We infer that late transplanting decrease the tiller occurrence and assimilate remobilization efficiency, which may be responsible for the reduced grain yield.
Background
Rice is a major cereal crop and staple food of eastern India, and most farmers depend solely on rice for their livelihood. Rice farming provides both tangible and non-tangible benefits to ...ecosystems which need to be maintained and enhanced. These benefits are provided through ecosystem services (ES) that include both marketable and non-marketable.
Methods
In this study, the rice farms in eastern India were valued by quantifying the economic value of the services under conventional method of rice cultivation and the gap of ecosystem services value and farm income per unit area were assessed. A stratified random sampling technique was used in this study for selection of agro-climatic zones, districts, blocks, gram panchayat, and study units (households). Soil sampling was also performed for assessing the regulating services (biocontrol of pests, carbon flow, soil erosion, nitrogen fixation), provisioning services (food and by-products), and supporting services (soil fertility, hydrological flow, nutrient cycling, and soil formation).
Results
The results indicated that the total economic value of ecosystem services ranged from US$ 1238 to 1688 ha
−1
year
−1
. The marketed (primary production) and non-marketed ecosystem services values ranged from 66–89 to 11–34% of the total, respectively. Valuation of some of the ecosystem services such as cultural services, biodiversity, and gas regulation, which may play a significant role in total ecosystem services, has not been made due to non-availability of data and appropriate methodology for rice ecosystem. Different values of parameters can explain the variability in ecosystem services among the agro-climatic zones in eastern India. Clustering of locations based on variability of ecosystem services helps in identifying intervention points for sustaining and improving ecosystem services, while permitting sustainable agro-ecological intensification. The highest total economic gap between ES value and farm income was found in the north central plateau zone (US$ 1063 ha
−1
year
−1
) and the lowest in the north western plateau zone (US$ 670 ha
−1
year
−1
).
Conclusion
We suggest various measures to reduce the economic gap, including payments for ecosystem services for rice farming for sustainability of the ecosystem and agricultural development, while ensuring reliable farm income.
Electroosmotic flow in micro and nano channels deals with the low Reynolds number effects due to weak inertial forces. It requires a very long channel for mixing of different species in low Reynolds ...number through diffusion. The motivation of the present study is to increase the mixing performance when more than one species with heterogeneous surface potential is considered. The generation of vortical flow due to the presence of wall heterogeneity at different locations of the channel is discussed. The flow characteristics for the present study are obtained by numerical solution of the Poisson equation, the Nernst–Planck equation, and the Navier–Stokes equation, simultaneously. A numerical method based on the pressure correction iterative algorithm (SIMPLE) is adopted to compute the flow field and mole fraction of the ions. The potential patch along the channel walls induces a strong recirculation vortex which in turn generate a strong pressure gradient to increase the mixing performance. The streamlines follow a tortuous path near patches.
NrfA is the molecular marker for dissimilatory nitrate reduction to ammonium (DNRA) activity, catalysing cytochrome c nitrite reductase enzyme. However, the limited study has been made so far to ...understand the structural homology modeling of NrfA protein in DNRA bacteria. Therefore, three model DNRA bacteria (
Escherechia coli, Wolinella succinogenes
and
Shewanella oneidensis
) were chosen in this study for
in-silico
protein modeling of NrfA which roughly consists of similar length of amino acids and molecular weight and they belong to two contrasting taxonomic families (γ-proteobacteria with
nrfABCDEFG
and ε-proteobacteria with
nrfHAIJ
operon). Multiple bioinformatic tools were used to examine the primary, secondary, and tertiary structure of NrfA protein using three distinct homology modeling pipelines viz
.,
Phyre2, Swiss model and Modeller. The results indicated that NrfA protein in
E. coli, W. succinogenes
and
S. oneidensis
was mostly periplasmic and hydrophilic. Four conserved Cys-X1-X2-Cys-His motifs, one Cys-X1-X2-Cys-Lys haem-binding motif and Ca ligand were also identified in NrfA protein irrespective of three model bacteria. Moreover, 11 identical conserved amino acids sequence was observed for the first time between serine and proline in NrfA protein. Secondary structure of NrfA revealed that α-helices were observed in 77.9%, 73.4%, and 77.4% in
E. coli, W. succinogenes
and
S. oneidensis
, respectively. Ramachandran plot showed that number of residue in favored region in
E. coli, W. succinogenes
and
S. oneidensis
was 97.03%, 97.01% and 97.25%, respectively. Our findings also revealed that among three pipelines, Modeller was considered the best
in-silico
tool for prediction of NrfA protein. Overall, significant findings of this study may aid in the identification of future unexplored DNRA bacteria containing cytochrome c nitrite reductase. The NrfA system, which is linked to respiratory nitrite ammonification, provides an analogous target for monitoring less studied N-retention processes, particularly in agricultural ecosystems. Furthermore, one of the challenging research tasks for the future is to determine how the NrfA protein responds to redox status in the microbial cells.
The theoretically predicted ferroelectric ZnSnS
3
film was successfully grown for the first time using spray pyrolysis technique. The trigonal structure of the films with x-ray diffraction peaks ...corresponding to (110), (211), (01-1), and (210) planes of ZnSnS
3
were observed. The direct energy band gap (
∼
2.62 eV) and an indirect gap (
∼
1.63 eV) of the films were estimated from the optical reflectivity spectra, and a broad photoluminescence emission peak was detected at around 2.58 eV. A band diagram was proposed to explain the optical properties of the film. The
P
–
E
measurement revealed that the grown ZnSnS
3
films were ferroelectric with a saturated polarization value of 20.5
μ
C
/
cm
2
. The Ni/ZnSnS
3
/FTO device shows a sizeable photovoltaic response with a maximum of 1.07 V (
V
oc
) and 1.03 µA (
I
sc
) under 532 nm light illumination with 14.92 mW/cm
2
power density. The nature of the observed current–voltage characteristics curves of Ni/ZnSnS
3
/FTO device for two different polarization states was explained considering the formation of potential barriers at the Ni/ZnSnS
3
/FTO interfaces and its modulation by the polarization-induced depolarization field. The overall photovoltaic response of the Ni/ZnSnS
3
/FTO system was predominant by the depolarization field over the internal bias field due to the Schottky effect at the interfaces. The maximum responsivity value at zero-bias conditions for ZnSnS
3
films was
1.45
μ
A
/
W
.The ferroelectric ZnSnS
3
could be a potential candidate for ferroelectric-based photodetector devices in the visible and near-infrared regions of the optical spectrum.
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